In a recent interview Bill Gates indicated that project Natal would not be a technology limited to the Xbox 360. It seems that Natal could be developed for Windows too.
Gates also indicated that Natal would not be just for gaming, it could be developed for content consumption, collaboration etc.
It is a very cool thought to think of interacting with your system in this way. Given the fast introduction of 3D capable displays, movies and upcoming games it seems that this would indeed become a push for PC makers and Microsoft.
When I first heard about this I first saw that scene in Iron Man where Tony Stark is making his new Iron Suit. Right after I envisioned Majority Report. Still it seems that the future is looking pretty cool, not only for gaming but for system interaction as a whole.