In order to port it to the 360, it would require some serious hacking, something that the free60 guys have been doing for months now, but still far from a running kernel(or any unsigned code for that matter).
Although the lack of access to the Rsx and the limited 256mb of ram, the Ps3 would be the best bet. I believe MythTV and ffmpeg guys are already working on optimizing their apps and codecs to work with cell's spus, and we should see nice softwares for the ps3 in 07.
Gentoo crowd is also working in a gentoo based distro, for the ps3, that will pack some cool tools for homebrew game developers.
There were some rumors of an opengl port to cell aswell, but I have found nothing so far.
