Besides the chatroulette meets facebook aspect, how is Airtime creating a live network that's any different than what Ustream and Justin.tv has already done?
Airtime is about extending your social graph one algorithmically-matched individual at a time (one-to-one). Ustream and Justin.tv are about broadcast channels (one-to-many) of which only a small percentage of the browsable directory are active at any point in time.
So it's chatroulette but with more intelligence using your FB social graph. Like "you might want to talk to this person because they like cats and are friends with your friend Jane." This seems to have good applicability in the dating world.