Sony's written a Folding@Home client for the PS3 and is getting excellent PR for the power of the Cell processor in the PS3. The various "@home" distributed computing projects struck me as a good example of the type of coding that was more likely to be possible on the XBox360 than amateur game coding.

Sadly, because XNA has locked out networking in its initial release, it doesn't look like an enterprising set of coders can write some optimized protein-folding shaders and get any work done.