With the fixed camera on the n810 it should be possible to have some motion/gesture detection like this by Gesturetek. Now we only need someone to er..program it, maybe based on Konfoos work? Nokia seems to be planning something like this as mentioned in this thread, that even involves two cameras for 3d detection. soo..maybe on the n900?

I'll see what I can do

Awesome! count me in as beta tester haha