As stupid as this logic is, a lot of people choose to stay with blackberry phones solely because of BBM. It has a way better interface for texting and in all actuality makes people feel exclusive and cool for being in the blackberry club... that said, I think Apple could draw a good chunk of customers if they offered, or a third party offered an app similar to BBM for the iPhone. With the push notification Apple will be offering I think this could work really really well. What would they call it? iPhone Instant Messenger? Apple iPhone Messenger (haha).