@Bas: I thought the tool chest was neat. Skeuomorphic design doesn't make sense on a flat screen, but it definitely makes sense in a 3D space. If I'm building something, I have a toolbox full of tools. Why shouldn't I have a toolbox when I'm building something virtually?
I think skeumorphic design makes sense on a flat screen too. When something is a new paradigm and people need to get accustomed to it, making it look and behave like known physical objects is a great learning tool. At some point though, people are so familiar with it that it's no longer necessary, and at that point all that stuff is just cluttering up the interface and taking attention off what matters. I'd argue the same rules apply in 3D. Sure, that toolchest is a great metaphor while we're getting to grips with virtual/augmented reality interfaces and gesture controls, but at some point we'll know exactly how to get around in them and the skeumorphism won't serve a purpose anymore.