I’ve been asked about selecting a Linux distro for use on the Playstation 3 a few times recently, so I’ve put together a page summarising some of the options which has mentions of pdaXrom, Debian, Ubuntu, Yellow Dog, Fedora, RHEL and Gentoo.
It’s all based on my own knowledge and experience – if there’s something you think is worth adding (or correcting, or improving) let me know.
[Update 20091021: Expanded the entry for Gentoo based on suggestions from unsolo & cheriff, and added a link to Windows-Hosted Cell SDK which I saw mentioned by @domipheus]