Have you actually used one of these things? I have been interested in the computer version of this since I saw them on /. a while back. If you can actually use them at somewhere near full speed it seems like they would be great for desktop use. No RSI moving back and forth to use the mouse. I use a trackball so if my right hand could stay on the trackball and my left on the keyboard it seems like this could be really productive with no elbow strain. But, I am a programmer so my typing speed is pretty important to me. I am curious how they would hold up under heavy use (10+ hours/day) since it seems like they are designed more for occasional palmtop use.

-Mike