Apparently for quite some time iChat and AIM have both had the ability to send SMS messages to mobile phones just by sending a message to +1 and then the phone number. Once the message is received it can even be replied to the AIM screen name. This is old news to a lot of people since this story was posted on macosxhints, Boing Boing, and Engadget way back in 2004; but I just found out and about it so maybe you didnt know.