Facetop superimposes transparent images of a computer’s desktop over video images of the user to allow the user to look at the video and desktop at the same time.
The video shows a ghostly mirror image of the user so that when he points, his video reflection appears to touch objects on the screen. The system tracks fingertip position in the video to allow the user to control the mouse pointer.
Essentially it looks like two users are working with a pane of glass containing the desktop between them. UNC is developing this technology as part of their research into software to aid in pair programming over a distance. Pretty cool. This is possible on OSX right now, but Windows folks will apparently need to wait for Longhorn for the neccesary support.