There's some new technology from JVC called "Slim HD-ILA Optical Engine" that allows rear-projection TVs to have a drastically reduced thickness, to the point that they can be mounted on a wall. The new engine has allowed JVC to reduce the thickness of its 56" rear-projection TV from 47cm to about 27cm.

The new technology is pretty heavy on technical details, but basically, the use of a concave mirror allows the light coming from the projector to be more focused than when using a convex mirror. This in turn means the projector can be closer to the mirror, allowing for a smaller body size.

More details are in JVC's English press release. A picture of a potential model appears below.