You don't gain much from this that you don't get from having a MDI window tiled against a bunch of toolbars. The idea of having toolbar items pinned to the "wall" is interesting, but in general I'd think it would just perspective-distort the icons used on the boxes/buttons.
Despite the obvious/intuitive feeling that if 2D is good, 3D is better, I think as long as we're viewing the desktop through a single 2D viewport there's really very little advantage to this.
On the other hand, as multiple displays are becoming more common, there might be an advantage to building an internal 3d model of a desktop and creating multiple viewports into this space with the LCDs. I don't think the Apple model shown in the link really aligns with that at this point, however.