Is there more to social gaming than 'Leaderboards' and 'Achievements'?

I upgraded my iPhone to use iOS 4.1 this morning, and the only real new thing that it offers for my phone (the 3GS) is Apple's new Game Center platform. This comes in the form of an app, requires you to create yet another profile (even if you already have an Apple ID), and then lets you connect with your friends. The major flaw here is that when you start, you have no friends, and the only way to add them is via sending or receiving e-mail invitations. Ouch! It's as if social network portability never happened...

No friends!

The problem I'm hoping Game Center will solve is that, once you've actually got some friends, it should make it easier to discover which games they're playing, and then to invite them to play [asynchronous] multiplayer games. At the moment, this process is really convoluted - the Carcassonne game uses an e-mail invite containing a link using a custom protocol which then opens the app, for example.

What I'm not so certain about is the concept of Leaderboards and Achievements, both of which are baked into the Game Center service. These may well be established game conventions, but as a non traditional-console-gamer, they feel awkward to me. Leaderboards (which keep track of high scores, both globally and amongst your friends) feel a bit show-offy, and don't offer much motivation when the high scores are enormous and unobtainable (for me at least). Achievements feel tokenistic, and as if you're being bribed to play the game for patronising virtual rewards. The Flight Control game, for example, includes 'achievements' such as "reading the game tutorial" and "landing an aircraft on each airfield", both of which require no skill and more-or-less amount to simply starting the app...

It's still early days, and perhaps these things will improve, but my initial feeling is that to make games really social, the rewards for playing should be meaningful and real, such as simply beating a friend in a actual game, or the ELO rating system (originating from Chess tournaments, and designed to be a zero-sum economy), or something intangible like learning something about yourself, or your friends, through the gameplay.