It began modestly: printers with scanning capabilities, cell phones with embedded cameras, or cameras with MP3 players. Then, at the Consumer Electronics Show this past January, the full-scale invasion of new “hybrid” products arrived: a combination mouse and digital phone. DVD recorders with hard disks and PC interfaces. Broadband home routers with both Ethernet and Wi-Fi interfaces. MP3 players mated with FM radios, CD players, satellite radios, cell phones – or anything else that would stand still. Luggage with solar panels to recharge gadgets. Printers that output to your TV (as well as paper).

Hybrid consumer-electronics products have arrived in full force – not unlike the flood of new combo foods that appeared in supermarkets in the 1990s, like kiwi-strawberry juice and salsa-lime-flavored chips. But whether or not most of these products will survive – and whether, in general, consumers want hybrid devices that can do many things fairly well or single-function devices that do one thing very well, remains an open question.

“You get to certain inflection points in technology, [with] manufacturers essentially trying to guess where the consumers want them to go, so they start throwing various combinations against the wall to see what sticks,” says Stan Schatt, vice president at Current Analysis, a market research firm in San Diego.

Even today’s most popular hybrid devices are still mutating each year. The latest digital cameras, for example, can double as credible video recorders. And, after years of denying that it had an interest in bringing out a video iPod, Apple did just that last fall. Meanwhile, for its Treo smartphones, Palm is ditching its much-loved Palm operating system in favor of Microsoft’s Windows Mobile.

So how soon will comfort and familiarity replace chaos? “It will be an ongoing battle for the next few years,” predicts Tom Dair, president of Smart Design, a product development firm headquartered in San Francisco. “There will be successes in both camps. There will be those who roll things together into a handheld and get the formula right. And there will be those who offer a good product stripped of confusing extras – and those will shine, too, since it will be obvious what they’re for and how to use them.”

Adds Dair: “I can’t confirm it, but I suspect that people would probably like to carry one device rather than five. If you could roll them into one device you might have a compelling offer for the consumer. But I don’t think that anyone has done it right yet.”

So what is the formula for success? “That’s our secret,” says Dair, “but it has to be part of a system rather than just a standalone thing. There has to be a product, a network, a service, and content.” Dair’s favorite example of a product-within-a-system is the iPod – which would be useless without a PC, the Internet, and the iTunes music and video download service. His favorite example of a hybrid standalone is the HP PhotoSmart Photo Printer, a portable unit that can process output directly from a camera. He happened to design that one. “No, we didn’t add an MP3 player to it – but that’s why it works so well,” he says.

Some hybrid combinations take a while to catch on. “The idea of TV on mobile phones has generated a lot of scorn, since the networks could not support good-quality video streams, and there was obvious criticism of the screen sizes,” says Kurt Scherf, principal analyst at Parks Associates, a market research firm in Dallas. “But now that wireless networks offer broadband speeds, and competition is driving carriers to deploy more multimedia-capable phones, we are going to see a lot more experimentation,” he predicts. “With 800 million cell phones sold yearly, appealing to the top-end five or ten percent still gives you a big market.”

Meanwhile, new multi-purpose devices continue to hit the market – in part because it’s relatively inexpensive to add functions. Building the ability to play MP3 files into a smartphone, for instance, can be as simple as adding a bit of software.

Mark Steiner, a principal at Steiner Design Associates in Stanford, CT, warns that this trend can cause confusion among users, though, if manufacturers start adding features indiscriminately. “As designers we are always talking to users to see what they really want from a product. But the engineers will say ‘Here’s what we can do – and at such little cost!’ and marketing will say, ‘Let’s do it!’”

“Most products will become smaller, and will have connectivity with other products,” says Schatt. “The question will be: How willing are people to sacrifice the best-of-breed for the convenience of all-in-one? We have already seen that process in the printer market [where multi-function units rule]. It will be another couple of years before things sort themselves out.”

Stephen Baker, an analyst with NPD Techworld, a market research firm in Port Washington, NY, suggests that “the trend toward hybrid products will continue until users say they don’t want it, they don’t use it, or it becomes irrelevant.”

Indeed, one product category that seemed red-hot two years ago – camera phones – may already be cooling off. Research firm In-Stat just published survey results showing that only 28 percent of people who own camera phones have transmitted pictures to friends or uploaded them to the Web for storage and later use.

“People who haven’t yet purchased camera phones are very enthusiastic about all the uses for their images,” says In-Stat analyst David Chamberlain in an announcement accompanying the report. “However, once they start using their new phones, they are turned off by perceived poor picture quality, slow network speeds, and the difficulty of creating and sending pictures.” Other analysts have a different take, though. They predict that camera phones will crowd out digital cameras at the low end of the camera market.

While some of the silliest hybrids – cameras with MP3 players and the refrigerator with a built-in Internet terminal – have already faded, engineers, designers, and industry analysts are certain to keep working on and arguing over what consumers really want.