IBM's Everywhere Displays project produces new touch screen

While the project has been going on for a while, the IBM Everywhere Display Project's latest interactive display combines projection with touch-screen technology in a manner that has curators around the world tight in the saddle.  The system uses an ED projector, camera, and mirror system to both project the interactive image and track users' movement, resulting in a touch screen on virtually any surface.  We just have one question:  What happens if and when the user gets in the way of the projector?