The current edition of the BBC program 'Click' has an interesting article on interfacing the new 'Kinect' controller with a PC.http://www.bbc.co.uk/iplayer/console/tv/b00w8kxc
During the program, the distance / 3d sensor is shown in operation using an IR-sensitive camera, and it's obvious that it's an IR laser, projecting through what I assume is a diffraction grating to produce a grid of dots. I believe that this type of projection is known as 'Structured Light' and is already in wide use in the computer vision systems used in production engineering.
Despite Microsoft's initial objections, Marcan http://exophase.com/19592/marcan-hacks-kinect-releases-open-source-driver/ has already released a 'C' library for the PC, and there are a burgeoning range of applications being found for this interesting piece of hardware. - see http://groups.google.com/group/openkinect/about
and http://openkinect.org/wiki/Main_Page
Such a relatively cheap 3D sensor and camera would make an interesting input device for laser control software, for example allowing projection of a beam that followed the outline of a dancer - or several dancers.
As all this is new to me and I haven't yet got my hands on one to play with, but I shall be watching the developments with interest.