COMPUTERS : 3D user interfaces

Sun have just released the source to Looking Glass, a 3D user interface. The basic idea is that normal applications are drawn onto 3D rectangles hanging around in space. The user can easily rotate their view to observe different applications in different 'places' - using a bit of spatial memory to remember where they are.
So how is this supposed to be superior to a 2D interface? I don't know, because you _don't_ have the ability to rotate completely up and down (as you would find yourself upside), and I don't think you can rotate the screen around it's centre (to get back to being rightside up).
In fact, from a topological point of view this is exactly the same as a 2D plain. Admitedly one that wraps at the top bottom and sides.
The big advantage of a huge, zoomable interface is that of spatial memory, and grouping. You can easily just plonk apps/documents down close to each other that are related, zoom out to a long way and then zoom in on another clump that you are now interested in. You can't do this in the 3D version because there will always be something behind you.
So what is the point? Bring on the massive 2D zoomable interfaces I say!! (Anyone wanna program one with me?)