According to website MacRumors, iMessage is likely to come to iChat. If true, this would allow users on Macs to talk to others on iOS devices such as iPhone, iPod touch and iPad. The users of the iOS devices would be able to send unlimited text messages to each other with the service.
It seems that some of Mac OS X Lion’s iChat code has some hints of what may be iMessage support. It seems that some of the extra bit of code in iChat for Lion may indicate the cross compatibility of iMessage for both Mac and iOS.