In movies like Minority Report usability experts always laugh as people use 3D interfaces to use a computer. 3D interfaces don't make sense they will say.
But as we start to make leaps in interface design we seem to be moving more toward gesturing to interface with applications.
The iPhone is a small example but this video shows a huge screen with an interface of only gestures (Video: you have to wait through a commercial). Is this just a technology demonstration or real world applications? I certainly can't tell.