(Update: Many — but not all — of the users in the Apple Support Communities are now reporting that the activation servers are back online, and their devices working again.)
Looks like the Lion Beta 3 Preview might not be the only problem Apple’s dealing with this morning.
As of last night, an ongoing problem with Apple’s activation servers seems to be leaving many iDevices recently updated or restored to iOS 4.3.3 bricked around the world.