As an iOS developer, sending out IPAs to be installed by users for testing and clients for review can be a nightmare experience. Over the past few months, I’ve become a regular user of this wireless app installation service called DIAWI – Development iOS Apps Wireless Installation. You can find it here: http://www.diawi.com.
You upload your IPA and your Ad-Hoc Provisioning Profile, and then send out the link to your users and clients. They use this link on their iOS device and get a web page that displays the Provisioning Profile (if it needs to be installed) and the IPA. Works very very well. I highly recommend using this website and service (and donating!).
