The introduction of support in OS X would be a great step to promote iMessage. After all, everything for this is: - iCloud has a shared address book - there is a great IM client iChat - add iMessage protocol to it and that's it.
Enthusiasts unearthed pieces of code in iChat: interface IMMessage: NSObject { IMHandle * _sender; IMHandle * _subject; NSAttributedString * _text; NSString * _plainBody; NSDate * _time; NSDate * _timeDelivered; NSDate * _timeRead; ')
But officially Apple is silent.
The iMessage application concept for OS X has appeared online. It was invented by the Jan-Michael Cart.
Personally, I do not see the point in a separate application, but how it will be in reality, I think that we will soon find out, because delay with the lack of support for iMessage in OS X is not in the interests of Apple.