Apple first introduced the new iMessage feature for iOS 5 back at WWDC 2011 as a unified messaging service that could deliver both text and multimedia messages over WiFi or 3G. It also offered read and delivery receipts as well as real-time typing indication. It was set to work for iPhones, iPads, and iPod touch devices. And now, it appears Apple plans on integrating the feature for Macs as well.
According to MacRumors, a developer revealed to them that there is evidence that iMessage support will be coming to the iChat instant messaging software on OS X Lion. Within the code for OS X Lion's iChat, there are two new properties called "timeDelivered" and "timeRead," which indicate the tracking of delivery and read receipts.
These features are offered in Apple's iMessage protocol but are not currently supported in iChat's native messaging protocols, suggesting that the addition of these two properties is for future compatibility between the two messaging services. iMessage is expected to arrive with iOS 5, which is rumored to launch in early October alongside the iPhone 5.