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Nope. It's kind of difficult to test, as the simulator only works between two WiFi connected simulators, and the device only works between two bluetooth connected devices. Since you cannot run two instances of the simulator on the same machine, it requires two Macs (and switching between them) or two devices to test properly.
 
Smule's Leaf Trombone has P2P in it. You can use it to play a duet with a friend.
 
I've made one that is currently in review for the App Store. It's called MultiTank and its a multiplayer tank game.
 
Apparently Tap Tap 3.0 (upgrade, not a completely new game like Tap Tap 2) will have peer to peer and maybe some way of creating your own tracks due to music library access
 
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