[masklinn]

As Timothee notes, peer-to-peer already exists, it was one of the big bullet points in iOS3, as part of the push towards improved gaming experience (which also yield GameCenter in iOS4).

I've yet to see an application make use of peer-to-peer communications at all (as well as in-game chat, though I'm pretty happy about that one).

[guptaneil]

I made a concept app that uses GameKit to share flashcards between iPads[1]. P2P in iOS is definitely underused, especially in non-gaming apps, but even GameKit requires some sort of connection setup. Having a zero-configuration P2P connection would be quite useful for many apps, such as Bump.

1: https://github.com/neilgupta/NoteBuddy