This is by far, the most innovative interface I've ever seen and am likely to see for the next few years at least. And yet, it's conceptually so simple (execution is everything) that it's really not particularly expensive, far cheaper than what it cost them to put together those simulated scenes in The Minority Report. Plus it could be extended to several several applications (yes, that's two severals) using Internet-based plumbing that already exists today.
View the video and be wowed. And I thought the bit where he walks up to his friend was just hilarious.
Video from here.