Why?

Those kinds of games are perfect for mobile devices. It's fun playing several games with complete strangers, there is always something to do.

I absolutely love Lost Cities (http://lostcitiesapp.de) which is similar in the way and situations it's played (it's a very different game but it's also turn based and uses Gamecenter for matchmaking. It's also best played with several people at once.)

We really need a robust version of Matchmaking that games like Halo have so that you're never without an opponent and a good connection.

Until Letterpress I had no use for Game Center at all, but I just used its auto-matching to start two engaging rounds with strangers. Fun game.

MS patented that matchmaking algorithm (even though it is very similar to the chess ranking algorithm ...)