Sven suggested that I post a followup to this bug because I recently encountered a related issue while testing debian-installer rc1 on my blue & white g3 PowerMac (for reference, bug #264963).
I am trying to get the machine to successfully boot after an install by the new installer, and I was asked to boot into "Linux emergency" and add a module to the hotplug and discover blacklists. I successfully booted into emergency mode, but I was unable to do anything useful because my keyboard didn't work. Since that machine doesn't have a serial port (nor do the newer PowerMacs), I was unable to use a serial console. Luckily I had another Linux installation on that machine, so I just booted into that, mounted the Debian partition, and edited the files that way, but obviously that strategy won't work for everyone. I agree with Sven that including the keyboard modules is pretty necessary on powerpc. For the newer mac models, this would be USB, and for older macs it would be whatever is necessary to support ADB keyboards. Thanks, - Colleen