The first PPC Linux I've used was Yellow Dog Linux 2.1 on a Power Mac 8550. I had it running with GNOME 1.x at the time and it ran decently. Since then, I've installed numerous distros on various Power Macs. I installed Debian Sarge on my old StarMax 4000. While I managed to get Ubuntu Warty to install at the time (despite not being supported), it was just a bit too much for that clone compared to Sarge. Since then, I've installed Edgy on my iMac G5 and it's really fast. I plan on putting Feisty on the iMac G5 really soon.