Creating a powerful new input device for computers is hard, but not as hard as convincing people to ditch the mouse for something entirely new. Like, say, waving your hands in the air. You can either hand them out on street corner (bad idea), or bundle them with a computer maker. Leap Motion is doing the latter.
Imagine a Microsoft Kinect on steroids and you have a good idea of how Leap Motion works. The motion controller tracks in-air movement to 1/100th of a millimeter. But instead of watching you dance, the Leap creates 8 cubic feet of 3-D space that is recreated on the computer and can be interacted with via hands, pens or random objects you find lying around your home.