Philippe Biondi and Fabrice Desclaux have stepped up to put and end to one of the most used software black box applications out there (besides microsoft products): skype. They managed to reverse engineer the protocol revealing all kinds of nasty stuff. They also show that it is possible to even create your own skype network with patched binaries! An interesting read. They also talk about skype talking to someone at night. I will never install such a beast on any of my systems...
[Stuff:skype_BHEU06.handout.pdf Read the paper here]