This page describes the status of the Debian Port for ["PowerPC"].

Older models work without any problem.

The new model have some issues to be solved:

iBook G4

Sleep-to-RAM still does not work. BenH is working on it. Sleep-to-disk does work with 2.6 kernels.

PowerBook 15"

AirportExtreme

It does not work and probably it will never work. It uses a Broadcom chipset and information has not been disclosed to create an Open Source driver.