I recently got an iPad 2, and the first thing I did after connecting it to iTunes was to upgrade it to iOS5. After I did, iTunes gave me the error “This device is not registered as part of the iPhone Developer Program”.
This is easily fixed, all I needed to do was log into the developer portal and add the device UDID, however the screen telling me this was preventing me from getting the UDID.
Eventually I managed to retrieve it from the Organiser in XCode. Glad I didn’t brick it in less than 8 hours, I can now play around with airplay once I’ve flashed my AppleTV.