Laptop-controlled projector based D&D table

Winchell sez, "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.

"This table has a lap-top computer connected to a screen projector mounted on the ceiling. It projects the currently visible parts of the map onto the tabletop. The referee can control which parts are visible via the laptop." Link (Thanks, Winchell!)