Now we?re hearing from an app developer that Apple is finally going to start rolling out a new beta program in the next few days. Details are slim, but it seems like Apple is capping the total number of beta participants at 100 per app. In order to download a beta app, users will need to submit their iPhone?s serial number to the developer, who will then need to flag its eligibility in the store itself. All betas will still be distributed through the App Store - you won?t be able to download one on an external site.
Full article at Apple Launching App Store Beta Program
There is also a new free app in the app store called Ad Hoc Helper. Which will email your iPhones UDID Unique Device Identifier to a developer.