I think the most elegant thing about this method is that it describes a scene in terms of its basic mathematical 3D objects and transformations on them (list here: http://www.iquilezles.org/www/articles/distfunctions/distfun... ) and then exploits the massive parallelism of the GPU for rendering all the pixels.

Here's a demo of someone playing around with it, complete with a Slisesix-inspired scene: http://www.rpenalva.com/blog/?p=254

This set of slides is also related: http://www.iquilezles.org/www/material/function2009/function...