Service design - phase two. Case Facebook

Earlier this week a radio-person on YleX was complaining about Facebook getting quiet. As she mentioned, the thrill of getting new friends diminishes after you got all your geek-friends invited.
-And like me, working and doing graduation thesis - the time window to create new contacts is quite small.

Then what? What's the catch and thrill at this point after the first service promise is experienced? -I hope there is, because not all have facebook as a shortcut on their mobile. And the users who see some trouble to see those notifications want the thrill, or turn into passive faces.