This looks really neat - thanks! We are going to look into the whole issue about material presets and libraries, and we want a preview not entirely unlike this actually
One of the problems is that SU doesn't have many standard texture mapping options. Cylindrical and spherical mapping are only possible with Ruby scripts. This means that a spherical materials preview scene is not necessarily the best way of displaying a material.
It won't be built into V2.0, but possibly V2.1. Let's see what's in SketchUp 8!
That which does not kill us makes us stronger