I just had my first game Poke Attack! accepted into the App Store 
It’s a turn based game (new to iOS 5.0) which relies completely on Apple’s Game Center & GameKit framework. I’m quite pleased with the way it turned out and it’s been a real learning experience. I’m kinda picky about small details and one of the things I would have liked to have changed about the game was the default game center notification sound.
For those of you that aren’t familiar, the default sound (low-res sample) is something like a trumpet from the Kentucky Derby. It’s odd, a bit annoying and almost every other game center game uses it.
Apparently up until iOS 5.0 you had no choice but to live with it. Thank You Apple for now allowing us to change the default sound! Not so much thanks for burying the instructions deep, deep in the documentation. I’m yet to actually find it in the docs and Google search returns nil.
I must give credit where credit is due – Jason Lust pointed this out over in the developer forums: Add a sound to the resources of your app bundle with the file name “GKInvite” of format “caf”, “aif”, or “wav”.
