I might be wrong, but wasn't skype's p2p system used mostly for udp hole punching? (i.e., the supernodes were used to initiate the connection and then the clients communicated directly with each other.) With the centralized system, do the call contents go through microsoft's servers now? (this should be pretty easy to prove, doesn't it? Just check the addresses where your UDP packets are being sent to and received from.) It just seems to me that if anyone wanted to spy on you, forcing someone else to migrate to an entirely new system would be massive overkill: Applebaum's talk shows there are _plenty_ of better tools available to get to your packets.

EDIT: This really seems like an interesting question: _are_ there any advantages an attacker would have with skype's centralized system that they wouldn't with their previous p2p system? From what we've seen so far, I think the differences (from an attacker's perspective) are trivial.