Look, what we don't need is ANOTHER chat protocol that is only available to those with iPhones. AIM/MSN/Jabber etc are supported on the iPhone already, and we can talk to people on computers, iPhones, or any phone with MSN/AIM/ICQ clients. An iPhone-only chat protocol is totally pointless. I don't care how many Blackberries you've owned or how important you may think you are. A proprietary iPhone-only chat protocol is NOT something we want or need. If you want something absurd and pointless like that, keep your Blackberry.
It IS just like AIM, etc. The only difference is that the messages show up. That difference will be eliminated once push notification is released. Then with AIM/MSN, you'll will get messages pushed to your phone, just like BBM. Only ... with AIM/MSN you will be able to talk to people who don't have iPhones, or are on their computers. In fact, phones like the T-Mobile G1 and the Sidekick and Windows Mobile phones already have push IM services. They use your data plan too.