Guys check out my homebuilt multi touch screen.
http://www.facebook.com/album.php?aid=35871&id=1727517574&l=faab92f74b
Any critisizim and advice Welcome .
what do you think
V 1.1 uses a converted IR camera(i also experimented with a wii mote) and it uses and ir pen.
V 2.2 uses a converted IR camera however it uses FTIR to detect fingers or any object, and can handle up to 50 touches.