The tech I have seen uses a pair of glasses with two tiny projectors mounted on the arms, these projectors bounce of the lenses and into your eye.
Head tracking is handled by a modified xbox kinect rather than having bulky accelerometers mounted on the glasses, also reduces power usage.
The display is quoted as being the same as a 14 FOOT projector screen 10 feet in front of the user.
Still experimental, and targeted at virtual reality instead of gaming, so the display is an overlay on the real world.
But hell, want one.