This morning I had the good fortune to be part of Enterprise 2.0's panel (chaired abley by Melanie Turek) on Presence 2.0. Five panelists, including myself, Parlano's Nick Fera, Microsoft's Paul Haverstock, IBM's Dave Marshak, and Jabber's Joe Hildebrand. The panelists universally viewed IM presence as an early presence application, and focused on where the future of Presence would be.
Probably the most thought provoking presentation of the five was Hildebrand's. He views presence as a collection of documents describing changes in your identity over a period of time. From that point of view, presence can include anything. I didn't ask the question, but he would probably view Facebook as a presence application.
The other intriguing presentation was Nick Fera's. The Parlano view is that by persisting chat sessions, one can tap into the collective intelligence of the organizations, and overcome many of the current limitations of presence.