I have seen the update yesterday, i think the problem was that this updater is included in 10.2, my G4 still runs 10.1.5 and somehow everything got messed up.
From the iBook i got the error message "could not read configuration on base station" while attempting to connect with the "airport utility". Even after updating to 4.0.6 the base station said it was on 4.0.4, after some time i couldn't connect from the G4 either, so i took the power from the ABS.
Other thing: I have had some noise on my stereo since i set up airport, like scratches and hissing coming out of the speakers. But during the time the airport wasn't running these noises were gone...
The say airport is 20 times less performant than a mobile, but it is running 24 hours a day opposed to my mobile which i often shut down.