I have some comments on the current Debian PowerPC port.
The testing and unstable distributions should at least provide a 2.6.18
or higher kernel. Here's why:
1) The stock kernel used on the Debian sarge and etch installer/livecd
does not contain thermal support for the Apple iMac G5.
2) The snd-powermac module causes the system to completey lockup/freeze.
This is a confirmed bug. It should, at least, for now be commented out
in /etc/modules.
3) 2.6.18 contains a new snd-aos which should provide sound to newer
iMac G5 models.
I hope the maintainers will notice this because it's very annoying for
people who want to try Debian on a iMac G5 only to find out that the
system freezes. This is very frustrating.