Just a caution, but if your friend is developing an app, that does not give him/her any rights to violate the terms of his developer's agreement, which means he has no legal rights to give unreleased Apple products to anyone, period. So, if you want to test for him, you need to be a developer too, in order to legally run the pre-releases of iOS (or any Apple pre-release software).
I just post that in case this is something they want to ultimately release through the App Store. If Apple found you violated the developers agreement in creating the app, I doubt they are going to be friendly about authorizing it for release through their store.
Of course, if he just gave you the final released version to get around the crowds plaguing the update servers, that's great.
Message was edited by: Michael Black