Here's an installation guide and first impressions for Ubuntu 7.10 on the Playstation 3
Read it here
For those of you who think for a second (and who are scared) that this will replace their PS3 operating system, well you guys are wrong, because this will NOT erase your PlayStation 3 native operating system (called XMB) and it will run as an alternative OS on your PS3 console. Ready? Are you excited? Let's go!