It's still in development (I need to add a few packages, like kexec-tools), but we now have a basic installation of the OpenWRT distribution on the PS3. This will make it possible to have a fully configurable linux installation that boots from the PS3's flash area. Once we have kexec working, you could use it as a bootloader, but it's also possible to add an ssh server, http server, or any of the standard tools available in OpenWRT.
If you try these out, let me know how you go.
Update: these patches have been accepted to the main OpenWRT subversion repository, so any revision after r9413 should work on the ps3.