As some of you might have attended yesterdays great fun of Stump the experts at the WWDC and my appearance, here's the actual question again with the correct answer (and proof via video):
[Caution: Sound has to be played after the question, call us to a microphone beforehand.]
Q: Which bug, present in a standard Mac OS X 10.3.4 installation, causes the following sounds? Name the application affected and describe the easiest way to trigger it on a PowerBook.
The Answer of the experts:
The bug is that the sound gets played overlappingly on a simple wake on the computer, and can be triggered via awaking in a large network. This is quite a lame and wrong answer. First: the played sound is the leaving sound, not the coming sound. Second: The sound is played ok, although it sounds a little weird. But this is not really a bug.
A: The bug is that iChat does not implement reference counting for Rendezvous services. In a multihomed networking environment this causes all Rendezvous buddies to disappear if one network device is disconnected, even though they are still online on another device. The easiest way to produce that sound is to run iChat and unplug the ethernet cable while still being connected with airport.
PROOF
P.S.: I accept your apologies :-)