I don't know how that user got two instances of it running simultaneously though. Maybe I'm using an older version.
Anybody ever use this?
http://www.hamar.sk/sphere/ -"SphereXP"
Check out Project Looking Glass too (google it), pretty cool stuff.
Although, I already have a brilliant 3D design in mind that makes more sense than either of these. They don't appear very intuitive or graceful. Let's see how Longhorn's 3D desktop goes.