There’s augmented reality by TAT, which does facial recognition to assign clickable metadata to a face (currently the metadata consists of different social media accounts).

Then there’s Layar, an application that can do “building recognition” (likely based on your location and the direction your phone is pointed instead of the actual picture of the building).  This is available for the Android OS, which is in use on phones such as the HTC Magic and the T-Mobile G1.  This is likely the same technology that we’re seeing in the new London Subway application (called “Nearest Tube” by acrossair) and the “stalk your children app” for the iPhone (below).

iPhone 3GS Augmented Reality from Chris Hughes on Vimeo.

And of course, the holograms on business cards that I posted a couple days ago:

Augmented Business Card from jonas on Vimeo.

The idea: A camera on any device would be able to see the tag on the card and then play a video or hologram that’s been mapped to the tag. With a little bit of image processing the device, be it a computer or a smart phone, would be able to position the video on top of the tag.

Can anybody think of a better idea than business cards though? Business cards don’t sound very exciting. A game using this idea sounds like a lot more fun.

Read more over at DigitalBeat.