Here’s a nice prototype of display by the University of British Columbia, pCubee :

[youtube]http://www.youtube.com/watch?v=89OoXyuxTLM&feature=player_embedded[/youtube]

It has no stereoscopic capability, but the parallax (movements of objects based on their depth) is enough for you to correctly perceive their 3d position.

We use magnetic sensor technology to help simulate real-time physics and to render coherent perspective for the user.