Things you need to know... no, really, this is important.
It's worth noting a few technical limitations with the whole procedure.Firstly, Linux (called "Other OS" in the PLAYSTATION 3 interface) can only be installed if one formats and repartitions the PS3's hard disk from within the XMB interface. You can either assign 10GiB to Linux, or everything but 10 GiB to Linux during the process, with the remainder going to the PS3 OS. Nothing in between can be set - but considering some of the console's games such as Ridge Racer 7 require up to a whopping 5GiB of space just for cache files, it's probably best to go with the former option.
Secondly, PS3 Linux can't communicate directly with the hardware - it runs inside a layer called a "Hypervisor", which controls and restricts access to the underlying hardware. The hypervisor does not allow any access to the RSX graphics chip inside the console, which severely impacts the GUI performance of distributions. It also makes it impossible to "properly" control the resolution used by the OS the same way you can with a normal PC distribution, so your chosen PS3 distribution must make it easy to select and use the right resolution. Oh, and the hypervisor only allows wired OR wireless networking to work, but not both at once.
Thirdly and finally, the hypervisor reserves a certain number of resources from the PS3 - so whilst the console has 256 MiB of RAM and 8 cores (1 real core and 7 sub-cores called SPEs), about 32 MiB of RAM and one SPE core are reserved for the hypervisor.
Beyond that, the usual caveats apply - the distribution needs to be recent enough to include drivers for things like the SIXAXIS controller or PS3 wireless connection. We're going to take a look at three distributions with proper PS3-targeted versions: openSUSE 10.3, Xubuntu 7.10, and Yellow Dog 5.0.1. Whilst there are a couple of others in existence, I'm excluding any distribution which does not contain everything required to install on the same CD as the OS itself - which means Gentoo and Fedora are out, for example.
Installing an "Other OS" on the PS3 first requires you to install a boot loader (like GRUB on PC distributions), and requiring you to install the boot loader from a different CD to the operating system isn't an acceptable solution as far as I'm concerned. Judging by some of the discussions over this (such as this one on the Fedora Project bug tracker) some distributions may well end up second-class for PS3 use forever.
Click for larger imageFrom within the XMB interface, you first need to select the "Install Other OS" option from within System Settings. This will read and install a boot loader from your install CD. Then, change the "Default System" option to "Other OS". This will cause the PS3 to always boot into your boot loader. To revert back to the PS3 OS (in event of problems loading it from within the boot loader), hold the PS3 power button on when booting, until it's beeped twice (but before it beeps for the third time).
So, with no further ado, let's look at the distributions!
