The last gestural interface demo I saw involved about a dozen precision cameras, several computer systems, two technicians and a lot of money. This system, developed by Pattie Maes and Pranav Mistry at the MIT Media Lab, costs only $350, is portable/wearable, works on any surface, and does the whole Minority Report thing about as well as I’ve ever seen…
More info: MIT Fluid Interfaces Group.
The goal of the Fluid Interfaces research group is to radically rethink the human-machine interactive experience. By designing interfaces that are more immersive, more intelligent, and more interactive we are changing the human-machine relationship and creating systems that are more responsive to people’s needs and actions, and that become true “accessories” for expanding our minds. (MIT Media Lab)
UPDATE: More info about this project can be found at Pranav Mistry’s site: http://www.pranavmistry.com/projects/sixthsense/