Linux On A RISC Box?

Noctrnl asks: "I've recently begun a search for a Linux distro to run on my old IBM RS/600 model 250 machines. A lot of PPC projects support the CPU architecture, but I have yet to find one that supports MCA on them. At every turn I can find a distro that supports the PowerPC chip on a PCI-based system, but have been unable to find a distribution that will run on my machines. Are there any projects underway that will allow me to boot a real operating system besides AIX on these babies? Just in case you were wondering, *BSD doesn't support them either."