Back in 2005 quite a few people got excited by a three-dimensional LED display unit created by art & visuals experts James Clar & Associates. Consisting of a lattice of 1000 white LEDs which could be individually controlled via an attached computer, it was held up as an eye-catching and intriguing promotional tool as well as a new spatial medium for interaction. The demo video of Pong being played in 3D is well worth seeing, and certainly makes you want a Cube of your own. At the time all they would say was that a commercial version was a possibility.
The latest news is that, as of October 2nd, the James Clar online store will open for business; the jewel amongst the (admittedly small) range is the 3D Display Cube. Identical in concept to the original, the unit has 512kb of memory capable of storing up to five minutes of video and comes complete with a serial cable and PC software to update it with your own animations. It isn't clear whether direct interaction (e.g. 3D games) is supported.
Costing a not-inconsiderable $3000, there's a two-week lead time before delivery.