Via Designboom:

Researchers from Disney and Carnegie Mellon University have developed wall++, a low-cost sensing approach that allows walls to become a smart infrastructure. A simple to apply treatment, wall++ challenges the inactivity of walls, turning them into a large sensor or touchpad.  Like a touchscreen phone the mutual capacitance is measured in between every wall and column pairs creating a matrix of values that allows the wall to sense the distance to capacitive objects like a user’s hand.

However, the video shows a rather complicated installation process.  If they turn this into a wallpaper type of product, it could be interesting.  Also, the electrical interference of electric appliances can be sensed – this could either be a “feature” or a nuisance depending on the application.  I wonder if this is better then even simple camera-tracking systems?

The original research paper can be found here: http://yang-zhang.me/research/Wall/Wall.pdf