Might be somewhat old news, but anyone else seen LeapMotion?
I only recently discovered it. Looks really cool though, and at 70$?? For real? Except they are not ready to ship yet, until end of this year or beginning of the next (and who knows, maybe even later. I have not preordered anything, mainly because I never really know when I'm broke and a bit skeptical about leaving credit card details to be withdrawn in 6 months time...)
It seemingly works by having two IR cameras and IR LEDs to light up whatever is above it, and (I guess) some on-board firmware to compute the 3D positions and report it via USB to a host computer. http://hackaday.com/2012/05/21/hackit-leap-motions-new-motion-sensor/
I also doubt it will replace the mouse anytime soon, but it would probably be a great addition for 3D work (and high coolness factor with iron man / minority report style control :P).
Now all that is missing is combining this with a true 3D display and touchable holography :D Except that laser is a bit unhealthy to meddle about with your hands (or eyes) for now..
(I'm not sure how to not embed a youtube video link)