It is always a tedious task to build an ad hoc IPA app for beta tester to try out your iPhone app. First you need to ask them the UDID, which they may helpfully give you a screenshot of iTunes... then you have to build an IPA, and prayed that they know how to do anything with the IPA.
Now, there is this "Hockey" framework (Announcing Hockey, an iOS developer framework) that can automate the process.
For integration sample, you might want to check out this PSiOSAppTemplate.
