It allows multiple points of contact, which means you can do things like drag apart with two fingers (or fingers and thumb) to scale, etc. or to join things together by simply dragging them together. From the video it seems like it really creates some intuitive and playful interaction. I’d love to see it in action. As Rob said, it’s very much a Minority Report-style interface.
Here’s the technical info from Jeff’s site:
The drafting table style implementation shown here measures 36″x27″, is rear-projected, and has a sensing resolution of better than 0.1″ at 50Hz. Stroke event information is sent to applications using the lightweight OSC protocol over UDP.
You should be able to view the YouTube video below if you have the latest Flash plug-in.