Not much info is known about this, it was slipped in at the end of there GDC presentation today. IGN of course was there so they have some info on it.

During a session given by Electronic Arts discussing the development of Boom Blox at the Game Developers Conference today it was revealed that head tracking will be included in the game as a hidden Easter Egg. A video demonstration was shown in which a brick structure was exploded and then paused. The player was able to move around the event in 3D and get an up-close look at the destruction.

Boom Blox players will be able to use any method they choose to control the head tracking. All that is needed are two infrared light sources in their hands or on their head. This can be accomplished by holding two Wii Remotes, or they could wear common safety glasses equipped with lights.