Layering data on top of smartphones and computer screens is both a fad and the future.

Why layering data on top of smartphones and computer screens is both a fad and the future. You wouldn't immediately suspect that Yelp's iPhone app might be a gift bestowed upon us by a benevolent superhero from the future. Load it up and the program's in its Clark Kent garb -- a useful-enough guide to local restaurants, bars, and merchants. Then you notice a button labeled monocle in the right-hand corner. Hit it and the screen displays a live feed from the phone's camera, showing exactly what's in front of you -- with one big difference. Aim the camera at a local storefront and Yelp superimposes a star rating on the image. Use Monocle in a hot neighborhood, for instance, and point it at every restaurant for a quick appraisal of the best food in the area. Yelp's app is one of the first "augmented reality," or AR, programs to debut on the iPhone, and though it can be handy, it's most useful as a sign of what's to come. Throughout the summer, YouTube was the place to see a vision of that future, as programmers from San Francisco to Malmö, Sweden, uploaded demonstration videos depicting such feats as recognizing a face at your high-school reunion while his social-networking pages pop up, or traveling back in time to view the Colosseum as it once existed. And then there are the really forward-thinking ideas. Babak Parviz, a bio-nanotechnologist at the University of Washington, has been working on augmented-reality contact lenses that would layer computer graphics on everything around us -- in other words, we'd have Terminator eyes. "We have a vast amount of data on the Web, but today we see it on a flat screen," says Michael Zöllner, an augmented-reality researcher at Germany's Fraunhofer Institute for Computer Graphics Research. "It's only a small step to see all of it superimposed on our lives." Much of this sounds like a comic-book version of technology, and indeed, all of this buzz led the research firm Gartner to put AR on its "hype cycle" for emerging technologies -- well on its way to the "peak of inflated expectations."

Marketers are as much to blame as geeks for the overheated environment. To date, the most prominent AR practitioners have been ad agencies, and Best Buy, GE, and Procter & Gamble have run campaigns. Most of them, unsurprisingly, were more gimmicky than useful. The central questions: Will people take to this mode of navigating information in the same way they've embraced social networking? Or will augmented reality suffer the fate of online virtual worlds such as Second Life, which attracted a torrent of attention but proved too cumbersome? Whether augmented reality emerges through this hype cycle depends on both technologists and marketers to peel away the great expectations and find something real. Augmented reality isn't new. The technology has been used for years in military projects as well as public spectacles such as museum exhibits and trade-show booth demos. The yellow first-down line superimposed on televised football games is an example of augmented reality. So why all the chatter now? "There have been a couple of game-changing events," says Greg Davis, North American general manager of Total Immersion, a decade-old French company that built these first-generation AR installations. "Consumers have access to AR on their home PCs, and now on their mobile phones as well."

Although Apple still limits how far developers can go with AR -- in particular, the phone's programming system prohibits apps from performing sophisticated image analysis on input from the camera -- the new OS is expected to usher in a rush of augmented-reality apps.