This was bound to happen. I remember lot of people from the announcement thread didn't want to try it by fear of being banned from Apple.
I really hope some country enforces interoperability of their services some day.
Do I need to quote Franklin? The best countermeasure to such a misbehavior from Apl is just to install Beeper by everyone and Barbra Streisand's effect will make Apple destroy the artificial fencing of Imessage.
