Someone has probably reported this already, but I've found what I think is a dealbreaker for me using iMessage on my iPhone 4. One of my friends upgraded to iOS5 and then got an Android phone. However, when he got rid of his iPhone he didn't remove his phone number from his Apple ID for iMessage. This means that when I (or anyone else with an iPhone running iOS5) try to message him, my phone chooses to send the messages by iMessage, despite him no longer having a phone capable of receiving the messages. I can't disable iMessage on a per-contact basis, so I can either disable iMessage completely for all of my contacts, or choose not to send him any more messages. Has anyone else encountered this issue, and is there a way to remove your phone number from your Apple ID so that people aren't sending you messages you can't receive?