It's just that the server part is now [theoretically] a bunch of servers in different locations [theoretically] to allow failover. Theoretically.
And yes, I'm almost certain that's Google's problem with the Skype model: no convenient place to stick ads. (OK, sure, the client app could just get ads from Google, but if the p2p voice protocol works w/o Google servers, you can write a client that avoids the ads.)