Jyri Engstrom and friends have released an early version of what they are calling a "mobile social phonebook". The application, called Jaiku, is currently designed for Symbian Series 60 devices. To quote the developers explanation:

"We invented the term 'rich presence' to describe the many relevant things a phone knows about you. Rich presence on Jaiku includes an IM-style away line, your phone profile (ring volume, vibrate), location (country, city/region, neigborhood), Bluetooth devices around, upcoming calendar events, and the duration how long your phone has been idle."

These extensions of simple on/off presence are valuable, because our states change, but our applications don't normally relay context of that change other than the binary on/off. Mobile devices uniquely change location frequently, and have several characteristics (profile settings that indicate our preferred mode of use) that are less evident in, say, a laptop.

I tried it on my Nokia 6682 Sunday just after it was released, and while the site-side chicklet worked, the phone app wasn't behaving properly. A new release quickly followed which I am installing now.

** One note, Americanos: Jaiku may use up to 10 MB of data per month to send presence data. Think carefully before loading it up.