theres a thread on how to get it legally, takes some work but not many people got it yet so... i think they havent yet officially released it.Mr_Prezident
Im pretty sure they did release it, its call YDL (yellow dog linux) and thats the only distro that availiable right now, but i have seen some movies on the internet of people running other distros somehow.
I run Yellow Dog Linux on the PS3 and I have to admit that for a "launch" product, it is VERY IMPRESSIVE. I like the fact that I can IM my friends, check my e-mail, type up documents (I'm typing this on my PS3 right now), and browse the web with a real web browser (Mozilla Firefox) on my PS3. As time goes on, they will only add features to this OS. I think it is the perfect compliment to the Sony OS that comes pre-installed on the PS3! If you have a PS3, a 60GB one in particular, I highly recommend you check this out!