There’s something called ToySight, which lets you play EyeToy style games with an iSight on a Mac.
It’s not quite what you want, but it does indicate that it’s possible to do something clever with cameras.
(I played with an EyeToy over the summer. I think I was about ten minutes in when I thought of the interfaces in Matrix Reloaded (the dock) and Minority Report, and how they might be kind of possible, but probably not that workable. (See also: Project Looking Glass.))
That does look a bit silly but still quite cool. And it’s by the ‘Strange Flavour’ people who’ve done the nice Airburst game before. I hope this game evolves nicely.
Btw, the article Iink to refers to the UI in Minority Report as well. IMO that UI was about the best thing in the whole film anyway.
Received data seems to be invalid. The wanted file does probably not exist or the guys at last.fm changed something.