Buried in the framework of OS X Lion's iChat, are two new properties (highlighted below):The "timeDelivered" and "timeRead' fields indicate the tracking of delivery and read receipts for instant messages. These features, however, are not supported in any of iChat's native messaging protocols,
You are mistaken. XMPP has had such features since 2002 (
XEP-0022), replaced now by
XEP-0184 as jtara says.
This could be no more than Apple trying to fill in the blanks in their standards support, though it would be nice to have a universal app handling video/audio chat and texts across Linux, Mac OS X, Windows, Android and iOS.
I don't see Apple providing the solution though, especially as they've yet to fulfil their promise of publishing the specs to Facetime that they made when it was first showcased more than a year ago.