If you haven't installed the OS yet, you'll find the Deb Wheezy images for PowerPC at http://www.debian.org/releases/wheezy/debian-installer/
I don't know what sort of mileage the other Linux flavours offer wrt PowerPC - I guess we might find out something more about that if you install a different one ;-)
I'm interested to hear how it goes for you.

Cheers,
Rob