Wasn’t that what you always wanted? Boing Boing: Laptop-controlled projector based D&D table
This is a fancy gaming table for Dungeons and Dragons-style role playing games. Typically such games are played with miniatures on a tabletop. The problem is that the players are only supposed to see the parts of the terrain that they have explored.
There are more details here:
http://www.enworld.org/showthread.php?t=122099
http://www.dundjinni.com/forums/forum_posts.asp?TID=1410&PN=1&TPN=1