updated 02:15 pm EDT, Wed September 14, 2011
iMessage may cross-pollinate between Mac, iOS
Calls for iMessage to reach the Mac may have been answered through discoveries made Wednesday. Elements for "timeDelivered" and "timeRead" receipts are in the framework of Lion's version of iChat that aren't needed for iChat's existing support but do reflect what iMessage would need. Although not certain, MacRumors extrapolates to anticipate that iChat will eventually get active iMessage support.
The timing for iMessage to arrive isn't clear, but it would presumably be active sometime after iOS 5 is available in the first half of October.
Apple's addition of iMessage is considered a foil to BlackBerry Messenger and has many of the same basic concepts, such as delivery, reading, and sending receipts as well as encrypted conversations. Its primary improvement comes from an intended seamless integration between devices and services. Unlike BBM, which won't work on a PlayBook without bridging to a phone, iMessage works on non-phone devices like the iPad and iPod. iPhone owners get an extra benefit as messages between identified iMessage owners automatically replaces text messages with iMessage and potentially saves money.
An iChat extension could give Apple a unique edge, since BBM by its nature doesn't work on the desktop.