I saw an image similar to this one on the Luxrender Gallery a long time ago. I decided to try to replicate it myself and ended up making my own changes. So I can’t take the credit for the idea but I did do all the work in Blender 2.49b and rendered (For several days) in Luxrender 0.6.
I seem to be having a strange issue with the URL. It is on “p a s t e a l l [dot] org” (no spaces).