iMessage | Daring Fireball
It also means iPhone users with iPhone-using friends and family no longer need SMS. I’ll cancel my SMS plan as soon as this ships.
(A well-informed little birdie tells me that Apple’s phone carrier partners around the world found out about iMessages when we did: during today’s keynote.)
If it sounds like BBM, RIM’s BlackBerry Messaging service, that’s because, well, it sounds a lot like BBM actually — and increases device lock-in as well.
SURPRISE! Carriers Didn’t Know iMessage Was Coming Until Today’s Keynote | Silicon Alley Insider