Presence Futures

I want to know the future of Presence, as I think it has to be the most important aspect of Web 2.0 (or perhaps it's 3.0).
Why is Presence so important? Because it changes the way we use the internet, fundementally.
In the past we all connected to the web, through dial-up or via office connections or a few of us even had broadband. After connection, we used a browser to search and look for what we want. But we were alone. I would compare it to going to a library, sitting in a padded cell and having to request books via notes addressed to the librarian, who would then push the relevant book through a slot in the door.
IRC changed that by creating chat rooms where we could interact, and IM integrated the chat concept into our desktops and made it less intrusive.
With the introduction of broadband on a wider scale, people became 'always on' and the separation of presence as a non-binary feature came about.
So what is it, and what will it become?
Today, even the most presence-aware applications do little more than publish your current status, with the more advanced ones providing minor additional information such as integrating the title of the track that you are currently listening to on the radio. The IETF paper on SIMPLE (extensions to SIP for presence), defines the person in the presence data model as:
Person: A person is the end user, and for the purposes of presence,
is characterized by states, such as "busy" or "sad" which impact
their ability and willingness to communicate.
But presence is much more than that, it is the social enabler of the web, and it changes the experience we have in using the internet.
Presence is about answering the questions; 'Who am I?', 'Where am I?', 'What am I doing/thinking?' (Cogito ergo adsum ;), 'What do I like/hate/want?', 'How am I feeling', 'Where am I going (today)?' and finally 'Who are you?'.
Presence is is immediate and it's personal, it varies by social environment and it will be the thing that drives all of our interactions in the future.

A true presence application has to have all the subtlety of facial expression and body language. It must allow our friends to know more about us than strangers, and it must allow us to be intimate with the people we love.

But the really interesting thing about presence is that it defines our immediate future, and that's worth a lot of Googledollars...