Sooner or later, we all face the Dodgeball truth. This comes at the moment when you realize that one of life’s possibilities – a product, an adventure, an offer, an idea – is really meant for people younger than you.

This bitter revelation is named for the relatively new Web-based service Dodgeball.com. This is a social networking site, and it represents most of what is supposed to be advanced and exciting about the current wave of “Web 2.0” offerings. Dodgeball’s goal is to help you figure out, at any moment of the day or night, whether your friends or people who might be friendly are nearby. Toward this end, users construct networks of contacts – you list your friends, they list theirs, and on it goes – and lists of “crushes,” people they’d like to get to know. Then, with your cell phone or PDA, you send Dodgeball a text message saying that you’ve arrived at a particular bar or Starbucks or museum. Dodgeball messages you back with a list of people in your network who are within brief walking distance of your location – and tells them, and your crushes, where you are.

Dodgeball clearly meets most of the standards Tim O’Reilly, of O’Reilly Media, laid out last fall in his manifesto “What Is Web 2.0.” (The paper can be found at tinyurl.com/cr5p9.) It relies on users to create and continually refine its content. It combines, or “mashes up,” different kinds of data and services: mapping systems, networking software, messaging services. (The single most annoying aspect of the annoyingly named Web 2.0 movement is the use of the term “mashing up” to denote what in English we call “combining.”) Dodgeball is light, mobile, interactive. And for the life of me, I can’t imagine when I would use it.

Well, I can. Two years from now, if I’m at the Republican or Democratic national convention, I might want to find the 100 people I know amid the 50,000 I don’t. Otherwise, I don’t need Dodgeball to find the people who matter to me. My wife is in the other room, my kids are with their cell phones, I can trawl for friends and relatives via BlackBerry. Dodgeball is meant for people in their 20s – my children’s age. Anyone my age who has signed up is probably also lurking on MySpace.

How did I come across Dodgeball? Trying it out was part of a larger journalistic experiment in living a Web 2.0-only life. For a couple of weeks this spring, I shifted as many of my activities as possible onto the Web, using new, hip technologies. Some of these shifts were merely the intensification of practices already familiar to many people – for instance, skipping newspapers and getting news only from RSS feeds and customized news sites. I listened to radio shows by podcast. I got my “authoritative” information from Wikipedia and all traffic and travel info from Windows Live Local and Google Earth.

I went further. I shopped for everything except food on eBay. When working with foreign-language documents, I used translations from Babel Fish. (This worked only so well. After a Babel Fish round-trip through Italian, the preceding sentence reads, “That one has only worked therefore well.”) Why use up space storing files on my own hard drive when, thanks to certain free utilities, I can store them on Gmail’s servers? I saved, sorted, and browsed photos I uploaded to Flickr. I used Skype for my phone calls, decided on books using Amazon’s recommendations rather than “expert” reviews, killed time with videos at YouTube, and listened to music through customizable sites like Pandora and Musicmatch. I kept my schedule on Google Calendar, my to-do list on Voo2do, and my outlines on iOutliner. I voyeured my neighborhood’s home values via Zillow. I even used an online service for each stage of the production of this article, culminating in my typing right now in Writely rather than Word. (Being only so confident that Writely wouldn’t somehow lose my work – or as Babel Fish might put it, “only confident therefore” – I backed it up into Gmail files. And being equally only confident therefore in Gmail, I cheated and made lifesaver backups on my own computer in Word.) And this is only an abbreviated list of what I did on the new Web.

There was one obvious conclusion to draw from this experience, and it’s the opposite of the Dodgeball revelation. A lot of these sites and services are terrific for people of any vintage, and they can handle more of one’s daily chores than I would ever have imagined. Their “social” aspect is valuable in small but real ways. After my wife and I made each other authorized viewers of our respective Google calendars, we didn’t have to bicker about whether we had already made dinner plans for three weeks from Tuesday.

Web 2.0’s most important step forward seems to be the widespread adoption of Ajax – a combination of XML and other technologies that can make a plain old Web page nearly as responsive to commands as a “real” application like Excel or Outlook. The beta version of Yahoo’s new mail utility is one illustration: it can move, delete, and offer previews of incoming messages just about as fast as my normal Outlook can. Writely is even more impressive. In all the usual tools and tricks of word processing – editing, deleting, changing formats, cutting and pasting – Writely’s speed, over a broadband connection, is hard to distinguish from a desktop version of Word’s; but unlike Word, Writely is truly of the Web. I could (had I wished) have shared documents and collaborated with fellow writers or edited my documents from any location.

Here is what you would know if you’d spent the spring the way I did:

The new Web is analog, not digital. By which I mean it is not the result of a single, big, discrete innovation. Rather, it represents a continuum of new ideas, from the slightly evolutionary to the dramatically different.

Consider the true darlings of Web 2.0, and the wide variation in the technologies and insights crucial to their success. Google Earth is entrancing because it combines extremely detailed worldwide imagery, technology that lets users “fly” from place to place, and a programming interface that lets users attach new data to images that they can share with other users. Google itself succeeded technically because of its PageRank algorithm for evaluating Web pages, but what made it so financially powerful were the AdSense and AdWords advertising networks. Skype emerged because its inventors were looking for a (legal) way to use the peer-to-peer technology that had gotten them into trouble as the basis for Kazaa, a file-sharing network. EBay understood the importance of “trust” rankings to allow sellers to buy from unknown vendors, but what made it king was the old-fashioned logic of monopoly, which means that once a certain auction site becomes popular, both buyers and sellers have an incentive to use only that site. Flickr, with its easy-upload systems and vast storage space, managed to keep pace with seven-megapixel digital photos and the proliferation of camera phones. MySpace and Facebook applied social-networking technology to the eternal interests of young people on the prowl.

These Web 2.0 companies are similar in that they’re all doing good business now; but they’re doing it for a wide variety of reasons and with wildly different histories and technical strengths. Their success is a welcome change from the Web 1.0 connotations of bubble, crash, and dashed hopes. But they don’t constitute as distinct a movement.

We don’t actually live in an online world. If, like me, you are constantly irradiated by Wi-Fi signals and have your BlackBerry always within reach, even at night, you may have begun to suspect that you are, if anything, connected all too much of the time. But that suspicion evaporates the moment you actually need information that resides somewhere, far away, on a server.

Google Calendar is great, but you can’t consult or change it while you’re sitting on a plane. The same is obviously true of online mapping, financial, social, and entertainment programs. For all its virtues, Writely is of no use at all if you happen to be having connection problems. This is going to sound like a convenient embellishment, but the records of my service provider, RCN, will prove that it’s true: for the last two hours, I have had a complete connection failure, so I’ve had to reconstruct this article from my “real” hard-disk files. (I am back with Writely now.) If you have any kind of life whatsoever, for several hours per day you will not be sitting at a desktop or laptop computer with a broadband connection. At those moments, Web 2.0 is for all practical purposes Web 0.0. Which brings us to…

Evolution still has a way to go. A crucial part of Homo conexus remains gravely underdeveloped – and as long as that’s the case, all these systems will fall short of their potential. The missing adaptation is a way to get information from the Internet when you have a signal but don’t have a keyboard. This is the dreaded realm of the handheld device.

Anyone who has watched 24 knows how PDAs ought to work. On the show, Jack Bauer is constantly having elaborate data sent to his PDA. The two huge limitations of real-world PDAs – that their screens are small and bad and their keyboards even smaller and worse – don’t trouble him at all. Today’s mobile handheld systems are very well adapted for voice communication and are usable enough for text messages and e-mail. But when you have to go to the real Web for information or services, as you must for many Web 2.0 applications, it’s usually not worth the effort.

Most is not all: or, the virtues of the short tail. Many Web 2.0 ventures are based on the familiar principle of the “long tail,” popularized by Wired’s editor in chief, Chris Anderson: that is, the idea that an accumulation of tiny, particular niche audiences can amount to a very large collective market. This is especially true for retailers (Amazon, eBay), portals (the updated Yahoo), and social networks (MySpace), and it explains the success of targeted advertising (Craigslist, Google AdSense). But those aspiring to use Ajax to displace desktop applications and services often employ an intriguingly “short tail” approach.

For years, software makers, notably Microsoft, have struggled with the bloatware dilemma. A small fraction of their users want specialized, elaborate new functions; moreover, the software makers themselves need to keep adding features to justify upgrades. But the more niche features they add, the more complex, buggy, and expensive their programs become, and the more off-putting they can seem to most users.

The likes of Voo2do, iOutliner, Google Calendar, and the new Google Spreadsheets have solved this problem by ignoring it. They do most things that most users of their desktop counterparts want – but almost nothing that the specialized user might. Writely lets me make bullet-point lists and choose from several fonts – but I can’t add footnotes or easily change the column layout. Google Spreadsheets lets me enter formulas and values as easily as Excel does, but it cannot produce graphs or charts. And the online to-do list systems lack some of the more sophisticated features I like in BrainStorm and Zoot.

The result of this short-tailism might be a curious new “long-tail” division between online and desktop applications: the free online apps will be for ordinary users under routine circumstances, while for-pay desktop apps may become even more bloated and specialized for high-end users. And to return to the original Dodgeball principle, there will be applications suited to users in each stage of life.

The new Web is digital, not analog. (See point number one; discuss.) By this I mean that the collective intelligence Web 2.0 supposedly marshals is most impressive when it sends big, distinct, yes-or-no signals, and worst when it attempts to offer more nuanced judgments.

For instance, eBay could not have gotten a foothold without its rating system, which establishes a track record for each buyer and seller. The system suffers from ridiculous grade inflation: “#1 AAAA++++ EBayer! Best ever!!!” doesn’t mean much more than “This person shipped me what she promised.” But if you see a string of 200 successful transactions with only two complaints, you feel better about sending off money than you otherwise could. The fruit of eBay’s rating system is binary information: this seller is okay, that one is not.

While such up-or-down judgments are generally useful, more refined distinctions, in my experience, are not. Pandora is a charming site that claims to have mapped the “genomes” of different kinds of music, so that if you tell it what songs you like – Chet Baker’s jazz vocals from the 1950s, say – it will bring you lots of other music that you’ll like, too. This is the audio version of Amazon’s ever-evolving list of book recommendations, based on your past purchases. Nice ideas, in both cases. So far, none of Pandora’s audio streams improves on what I’d choose for myself from its library of recordings. To be fair, I have learned about some artists I wouldn’t otherwise have come across: for instance, after I told Pandora that I liked the French gypsy guitar virtuoso Biréli Lagrène, it came up with the improbably named The Frank and Joe Show. But in nearly a decade with Amazon, I’ve yet to experience the moment of perfect serendipity when it discovers a book I really like that I wouldn’t otherwise have known about.

All this outpouring of knowledge is inspiring. If you were more churlish than I am, you would end up mocking the vast tonnage of earnest self-expression, the narcissistic self-documentation (in the form of Flickr photos), the craving for contact, the blog-based disputation, and the effort invested in metatagging that characterize the interactive Web. But I am not that churlish. I find it admirable, and deeply human.

But it is also potentially tragic. Many new Web applications are explicit about the importance of trust. You indicate your trust of certain reviewers or business partners and your mistrust of others. You build networks of contacts, and cross network barriers, based on stated trust levels. Wikipedia survives because users trust that, in general, it will be accurate, and seldom manipulated or simply wrong. Google’s PageRank is one of the most important structural indicators of trust.

In fact, every bit of the Web enterprise operates on trust. Web-based commerce has gone as far as it has because of the surprisingly low level of fraud and error. Much of my financial life is now online – paychecks deposited, checks paid, 401(k) accounts fretted over, taxes filed. And increasingly, my communications are, too. The telephone barely rings these days, although I’m in better touch with more people, via Skype and e-mail, than ever before. And all this depends on the basic trust that messages will go through undistorted, unintercepted, and in general unimpeded.

In principle, we all recognize that nothing on the Internet is ever truly private. Messages sent from company e-mail accounts are in theory the company’s property. Downloaded data passes through so many servers that it is no doubt stored by countless parties other than the sender and receiver. So far, for most people, this has seemed more a hypothetical problem than an urgent and unavoidable one. But if that changes, it’ll mean a moment of Dodgeball truth for all of us, when we recognize that the Web 2.0 era belonged to younger, more trusting people.

In practical terms, where does this leave me? With the experiment over, I doubt that I’ll use Writely again. (Yes, it does most of what I want in a word processor – but so does Word, and I can use that when I’m sitting on an airplane. Same for Google Spreadsheets versus Excel.) Maybe I’ll check out YouTube when someone sends me an interesting link. I’ll look at Wikipedia pages when they come up high in a search and I have a way to double-check any crucial facts. As for MySpace – nah!

But other applications have come to seem like natural parts of my daily life. Google Calendar is worth the effort – for the appointments that my wife needs to know about. I find that I leave Google Earth running all day, to check aerial views of a foreign site I’ve just read about or a neighborhood where I’m meeting someone for lunch. The discount travel broker Kayak has gotten my attention; eBay has retained it, for all the obvious reasons. Flickr is a good way to share photo files with my family – and keep them from jamming up my computer. I’ll continue using Gmail as a backup site for important data files. As Ajax-enabled sites spread, they’ll make sites that still require you to hit “refresh” or a “submit” button seem hopelessly out of date. I still don’t like the label Web 2.0, I will continue to mock those who say “mash up,” and I will never use Dodgeball. But I’m glad for what this experiment has forced me to see.

James Fallows is a national correspondent for the Atlantic.