interacting with the webcam

OK - there's no other way to say it - THIS IS RAD.
Assissin's Creed 2 has launched a teaser site. After a beautiful video intro, featuring some bits of Da Vinci's sketchbooks, you arrive at screen with a symbol in the center.
When you click on the symbol, it downloads a PDF.
The PDF features the same symbol from the website, with instructions in the bottom left:
1. PRINT ARTIFACT SYMBOL
2. LOCATE WEL LIT WORK AREA
3. ACTIVATE LOCAL WEBCAM
4. INITIATE VIRTUAL INTERFACE
5. DETERMINE MATCHING PARTITION
After I begin the steps, this happens:
ac2_analyzing.jpg
ac2_validating.jpg
ac2_hand01.jpg
ac2_hand02.jpg
It might be hard to tell, but in the last 2 photos, the virtual hand is actually mapping in 3-D space as if it was attached to my piece of paper.
Much like the world of multi-touch computing, this is just the beginning of virtual interactions and camera manipulation we'll be seeing on the web.
*On a related note, check out the sites Pioneers and Publicis & Hal Riney, which also explore alternative navigation techniques with webcams.