I put Fedora 9 on mine. It took forever to install. The X Windows experience is very poor, but I'm quite excited about one day being able to write for the multi-core SPUs. I've been working on a project in Windows which allows me to break down and farm-out image processing jobs, with the intention of being able to port it to PS3.
<edit> Actually, it was Fedora 8, which means I'll need to update everything. Again.

Jim