As a WindowBlinds 5 user, I have to say that I was really disappointed in the funky way my desktop folders appeared, when I opened them. My AeroGlass effect was gone... sort of... about 30% of the effect showed up when I moused over the open folder, and still there seemed to be a duplicate window open behind it, that was skinned with the Windows Classic skin...
Of course, once the folders were moved around in the sphere, they seemed to have their own default graphics assigned to them, and they looked okay when I reopened 'em using the Sphere images. So I'd call this an interesting idea at this point, but really ugly to use until it's more developed to be compatible with WB. For all I know, though, for non-WindowBlinds users it might be a godsend.
One thing came out of this, though... I've got .Net Framework 2 installed on my machine now...