Once Lion comes out, Mac will gain iMessage support. One of the features in iOS 6 is the unifying of your phone number and Apple ID. I have an iPhone 4S and an iMac. I plan to use iMessage on my iMac once Lion comes out. But how will I be able to use it in conjunction with my iPhone if my phone number and Apple ID aren't unified, which I will have to wait for iOS 6 to do?