if im not wrong.. i have an app that i downloaded on the app store where i can send and receive files from another iphone over the same network.. and it did for my gf's iphone and mine.. but i dont think can send with other phones.. also, another one while lets you transfer songs and mainly all kinds of files through network from computer to iphone. hope that helps.. my phone is not jailbroken btw..so it can do so much already.. imagine with it JB...
Yep, there are applications which allows you to do file transfer via iphone.