I just found something that I THINK wasnt in the Iphone before the 2.2 update, and I have no idea what it does. I understand the concept of adhoc, but why an expiration date?
This is an iPhone developers' certification mechanism. A provisioning must be obtained from Apple before being able to test the code on the real phone. Not sure how you got that on you though, someone else borrowed your phone and did a bit of development and testing?