Virtual reality researcher Hiroo Iwata has developed cubes that utilize a pressure-sensitive fabric and ultrasonic sensors to predict movement, analyze positions and shuffle accordingly. Essentially, this creates an "infinite" walkway.
As you can see in the video, the walking pace is a little on the slow side, but Iwata believes that refinement of the technology could lead to more realistic virtual simulations. Throw some lights in there and I smell an awesome redux of "Billie Jean" for the 21st century. [Technabob via Popular Science]