While writing my Silverlight wish list I found a very nice project. Johnny Ching Lee  is using the controller (Wiimote) of the Nintendo Wii to track fingers . The controller does not need the Nintendo Wii  console, simple the controller and a bluetooth connection  is enough. Combining this project with WPF or Silverlight would be the answer of one of my wishes. (Well, I know what I will try during the holidays.)
Other Finger Tracking Systems
In the following short video Michael Dell shows the new Dell  Latitude XT which has multi-touch capabilities. I'm very tight if this type of Tablet PC will be available next to buy. I will be one of the first, sure.