Fujitsu wants to enable you to type when you don’t have a keyboard handy:

The way the entire thing works is as follows: the fingers hit the surface just as they would do on a physical keyboard. The tablet’s webcam picks up these movements, which in turn is the only input for the underlying software. The software will process the finger movements and compare those gestures to what they would have hit on a physical keyboard. That’s pretty exciting technology, though it is still in the early prototype stages.