My scheme to naively install Fedora's undocumented ppc64 RPMs from the development branch onto a spare partition on my G5 seems to have worked. I can now boot and run a very basic ppc64 system (after adding my own fedora-release rpm). It is possibly the most basic system where you can edit things (vim), install stuff (rpm) and grap stuff off the web (wget), but it does work. I still don't know whether the ppc64 packages were meant to work or not or what the people at Red Hat were thinking when they compiled them, but I'm happy.
Did you know that rpm has over 50 packages it depends on either directly or indirectly. There are the obvious ones like glibc and it's a good thing that SysVinit show up eventually. However you also need glib, both versions 1 and 2 ! The upside is that you by just fufilling the requirements for rpm and you have everything you need for a basic, bootable, system.
Fedora really freaks if you don't have an fstab file. It's kind of fun seeing how well (or badly) a system handles itself without even basic configuration. For the record, Fedora does well enough: you can creat the fstab file from within Fedora.