Someone went digging through the iOS 4.3 code and discovered the same code for the A5 processor in references for both the iPad 2 and iPhone 5. I don't think this was ever really a question, but if you need every bit of confirmation you can get, there's some more. [Filippo Biga via Electronista]
I don't quite see how they can make the iPhone perform any faster than it does now. An A5 processor won't provide much noticeable speed difference when doing everyday tasks with the phone.
Early reports of the iPad 2 say it's not THAT much faster than the original iPad and the iPad 2 has the same A5 processor.
If Apple wants my money for an iPhone 5, it needs to be on AT&T's 4G LTE network.