Bear with me; this is the strangest thing my phone's ever pulled.
Today I restored my phone in order to upgrade to the iOS 5 beta (3) from 4.3. (Yes, my UDID is registered by a developer, though I do not own the developer account myself.) The restore went perfectly (using the correct ios5 ipsw), and then I selected the backup I had made this morning and it too completed successfully... Except that throughout the process, and after it finished, the phone just displayed the apple boot logo. It shows up in iTunes and allowed me to sync, add music files, fiddle with settings, etc, but the screen stayed stuck. I ejected the phone and waited a while, then turned it off (popped back on with the apple a second later), then reset it. No dice.
I then (rather unhappily, as this whole process had taken a couple hours) put my phone into DFU mode and went through the entire process again. As soon as it finished restoring from backup it went straight into a sync, which it has been processing for the last few hours. (I know. I have too many apps. Still, this seems like a ridiculous time, though the progress bar is scooting along and showing what it's doing consistently.) The screen is still the apple logo.
Curiously, this time around, I noticed a small exclamation next to the eject symbol, but I can not figure out (nor discover through google) what it's trying to tell me. If I click it, it just disappears. Helpful.
Oh, and throughout I have not received any error messages. (And yes, I installed iTunes 10.5 [beta 3] before starting all this.)
The most frustrating thing is that twice now my phone has made the little "new mail" chime completely randomly, as though it's "working" but just not displaying what it should be. I don't get it. And it's been doubly frustrating since I was so psyched to try out iOS 5 this morning.
This poster seems to have had the same problem, but the issue was never resolved: https://discussions.apple.com/message/15195656#15195656
Anyone got any ideas?