I need a little help with 3.0

Go to the Dev Center and add you device UUID, will be activated in 1 minute

 

Well you need the latest version of Xcode (3.1 I believe, correct me if im wrong)

You shouldn't have to mess with your iPhone's OS seeing as 3.0 is already on there. if you do though.. just restore to the 3.0 beta (should work. i havent tried), then after adding your UUID to the list iTunes should activate your phone. Then when you open xcode i recommend deleting all the phones from the list on the left so you can start fresh with a higher chance of success. So just connect you phone and it will ask you to add a new device that is registered as a test device and it should work from there. I don't know much more than that. GL

 

You'll need to downgrade .. this works to be able to get the 'Unique ID" via xcode and then register the phone.

If you read all the items in the developer area, it does help.
Just upgraded mine to beta 3 and all seems to be working well.

 

You can find your correct UDID by attaching iPhone to USB and navigating to System Profiler > USB

Perhaps you missed a character?

 

I don't think he'll have to downgrade.

OP: Just go into the iPhone Dev Portal, follow the steps to register your UDID (just click the serial # in the summary tab in iTunes when your iPhone is plugged in. Next, open the 3.0 SDK version of Xcode, open the Organizer, and restore to 3.0 again. Then open iTunes to get it activated and you should be good.