I have been using Linux for 10 years now. I have had my PS3 for about a year, and still don't have much of a desire to install Linux.
I think most people would be better served by installing linux on a desktop, and playing with it there. Most linux installers now will even partition your windows install, so you can have windows hold your hand while you learn it.
Unless you need another desktop/workstation, or plan on using the PS3 as a web/ftp server, I don't see the point, other than bragging to your friends. With 256 MB of main, you can't even run a newb-friendly desktop environment like KDE, or GNome all that well. Possibly XFCE would be ok.
If you must: Having tried many distros, I would second Ubuntu or KUbuntu (I prefer KDE over GNome), as very newb-friendly. Once you have picked a distro, use the distro's community forums to learn linux. You'll get a lot more answers than here.
~S