iOS developer @Gojohnnyboi discovered some code in iOS 5.0.1 that could indicate iChat -- Apple's Mac OS X instant messenger client -- functionality may be coming to iPhone, iPad, and iPod touch down the road.
Although the new iMessage feature in iOS 5 doesn't hook into the same chat services mentioned in the code, it would make a lot of sense for Apple to ultimately streamline the iChat, FaceTime, and iMessage into a single service across Apple devices.