The Wall Street Journal reported this weekend that some Facebook applications--such as games--share the unique number assigned to each of the social network's half-a-billion members with third-party companies including advertising firms. But this latest Facebook privacy scare has actually been brewing for more than a decade. It's all down to a "vulnerability" that was described back in 1999 by Tim Berners-Lee and others working on version 1.1 of the HTTP standard, and which underlies the Web: "The Referrer header allows reading patterns to be studied and reverse links drawn. Although it can be very useful, its power can be abused if user details are not separated from the information contained in [it]."

Here's what that means: Every time your browser loads a new Web page, or a section of one, the server providing the data gets to know the address of the page that sent you there. The same process is at work when you're interacting with an app inside Facebook, which means the app gets a Referrer header containing your unique Facebook ID. That ID is not exactly on a par with a Social Security number. It's a public number that can be used to pull up the public version of a person's profile page, which shows no more than a person has allowed to be seen publically. In most cases it's enough to reveal a person's name, though.

It's not unusual for apps and Web services of all kinds to bundle up metrics and data on their users to share with third parties, and The Wall Street Journal says that bundles from some apps have contained user IDs. Facebook says that in most cases app makers "did not intend" to share IDs and it has reinstated some apps that suddenly disappeared after the Journal's story appeared. As yet, there seems to be no evidence that user IDs were sold intentionally, or used to guide marketing efforts. It's also debatable whether your ID number counts as personal information, and the extent to which Facebook was culpable. On the latter point, it's clear that anyone with a good technical knowledge of the Web would be familiar with this somewhat ancient feature/bug of HTTP, including many at Facebook and elsewhere.

That being the case it seems surprising that, first, there's apparently no established way to cash in on it and, second, no systems exist to head off the issue. As for a fix, one approach would be for companies like Facebook to design their systems to alter this built-in behavior. Another would be a clean-slate redesign of the Web, preventing the need for case-by-case fixes.

The latest version of Apple's Web browser, Safari 5, sports a feature called "Reader" that concatenates the multi-page articles seen on most news sites (including Technology Review's) into a single scrollable window. According to Apple, the stripped down format "removes annoying ads and other visual distractions from online articles."

It, of course, also removes advertising revenues from the people who created those articles. Ad blocking software is nothing new; personally I've appreciated the option to block pop-ups that are incorporated into most modern browsers. What is new is that Apple doesn't give the user the option to not block ads in Reader. This option wouldn't be technically difficult to add in comparison to the work Apple has already done on developing Reader: most websites already provide links to stripped down versions of their articles, under a "printer-friendly" link, which contain one or two static ads that could be integrated into the Reader presentation of a story without being disruptive.

Why would a reader want an ad-enabled version? Well, for the same reason I don't install any of the freely available ad blockers; I'm happy to support sites that I think strike a reasonable balance between advertising and content. Having to, say, watch a few 30-second commercial breaks in exchange for free video-on-demand from Hulu seems a fair deal. Similarly, seeing a few display ads scattered around a news article also seems like a fair exchange for original reporting and writing. But Apple's Reader doesn't give users the flexibility to make that choice; if they want Reader's functionality, they have to accept its philosophy, which is firmly oriented towards what's best for Apple, not users.

Some have interpreted Apple's ad-less Reader as a blow for the little guy. But I don't think Apple really cares about sparing surfers from advertising; it seems more likely the Reader is designed to push publishers towards delivering their products via custom apps on the iPad and iPhone, where ads can't be blocked. And if, as Apple hopes, publishers serve ads using Apple's own iAd platform, the company will happily take its 40 percent right off the top.

I can only imagine how loudly Apple would complain if news websites retaliated against Reader by blocking Safari outright, and heaven knows no-one wants a return to the days when many sites came with a notice stating "Warning: Your browser is not supported!" if you dared to visit them with anything other than the one or two browsers that had been officially blessed. Instead, I hope a balance between Apple and content providers can be struck, perhaps as simply as by adding a "Display printer-friendly ads" checkbox in Safari's preferences.

Within three-to-four years, Google hopes that its Apps will be more than a billion dollar revenue stream for the company, according to Nikesh Arora, president of global sales operations and business development at Google, who was speaking onstage at the TechCrunch Disrupt conference in New York City.

Google has seen huge growth this decade. When Arora came to the company in 2004, the company was pulling in about $2 billion a year. Today, Google's revenue is $24 billion. This comes almost entirely from its search advertising business, but Arora laughed off suggestions that Google is a "one-trick pony," but. "It's a pretty good trick," he said. "I love that trick." He also pointed out that search is not one trick in itself--the company has had to do a great deal over the past 10 years to serve the different categories that people search today.

Arora believes there's much more to be had from the online advertising market. He estimates that the total online advertising market is about $50 billion a year, but expects that number to grow fourfold in the next five years. Google currently owns about half that market; and Arora coyly stated the company would like to continue to "participate" in online advertising as it grows.

Arora said that current trends in startups hint at the growing importance of applications in the cloud, and he did not contradict the suggestion that Google was looking to its apps suite as its second trick. Most innovations today start out aimed at consumers, he said, and slowly make their way into enterprises. Arora suggested that Google will pick up market share for its Apps by appealing first to consumers and small businesses.