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.