Jeff Han's Multi-Touch Interaction Screen.

A very cool invention - can't wait till it becomes a mainstream application:

These go far beyond the "poking" actions you get with a typical touchscreen, or the gross gesturing found in video-based interactive interfaces. It is a rich area for research, and we are extremely excited by its potential for advances in efficiency, usability, and intuitiveness. It's also just so much fun!

Link - the video will probably load slowly, due to this webpage's insane popularity on the Net now. (Thanks Nick Kochakian!)