Yellow Dog Linux (YDL) was the first out of the gate with their version of Linux for the PS3 available on launch day in the US. Next came news of Fedora Core 4 available for installation. Next up is Debian, with their version of Linux available for doanload and install on the PS3.
Apparently hardware support is limited in each of these distros, but I understand YDL has the best support so far, but it is still limited to access only 1 of the 8 Cell Processor cores, and doesn’t not have exclusive access to the PS3 NVidia RSX graphics chip, so you won’t be seeing any hot home-brew games based on Linux taking full advantage of the hardware just yet. Still, if you’re looking for a running general purpose OS to use from your sofa with a wireless keyboard and mouse, then there are a number of options out there.