Hang around the instant-messaging and mobile-messaging worlds long enough and you'll hear a constant stream of discussion on the importance of presence and why it's essential to the growth and eventual convergence of both spheres.

Presence, to put it simply, is the ability for IM tools to know where you are and your state of availability. Currently presence is a binary state in mainstream commercial IM applications: either you're available for chat or you're not. Sure, you can throw up an Away message when you sneak away from the office, but that's just another way to tell someone you're not really available for chat.

But the future of presence lies in its contextuality and the ability to add rules to presence. Instead of just knowing if you are available, the messaging tools of tomorrow will know the extent of your availability -- whether you're able to receive files or only text messages, who precisely can contact you, if messaging should be enabled based on your current workload, and under what circumstances should you be contacted. And while some IM tools have interesting group-management tools (most notably Odigo), these tools still need to migrate to widespread usage.

One interesting start to adding presence to commonly used instant-messaging tools is BuddySpace, a cross-platform Java application based on Jabber. Developed at the Knowledge Media Institute in the United Kingdom, BuddySpace is open source and available for download for use on Windows, Unix, Mac OS X, and Linux.

While the approach may be overly academic -- the announcement from the BuddySpace folks at The Open University in England says they are "studying the semantics of presence, in order to move beyond simple flags such as 'online' and 'busy' to include rich contextual, spatial and temporal information" -- the resulting software is an interesting view of where instant messaging is headed and how it will be.

Still, BuddySpace shows the difficulty of adding presence in a meaningful way to an IM applications that relies on a traditional computer desktop. Presence in BuddySpace can be one of five settings: free to chat, away, extended away, do not disturb, or a custom message. (By comparison: AOL Instant Messenger gives you the same capabilities.) More interesting is the software's ability to place users on a map, albeit "at a suitably coarse-grained level that your privacy is not violated," according to the documentation, and then display the status of the location on ay custom map. The default installation has some map examples, ranging in scale from an office suite to a hemisphere, and you could conceivably create your own using the open map format.

To their credit, the BuddySpace developers outline the problems inherent in adding presence tools to instant messaging. It's clear that the variables needed to relay a person's true state, such as adding the ability to filter based on workloads and physical locations, are still beyond the realm of current IM tools. And it's going to take something more than simple Boolean logic to move presence into the mainstream.

You should download the Java client and take a look at the BuddySpace Web site. Be warned that BuddySpace is still rough around the edges -- it loads from a DOS batch file on a command line under Windows, and some of the icons are pixelated as they are sized beyond their normal sizes, for instance -- and unless you're going to spend a lot of time setting up your own Jabber workgroup, it won't be much use except as a proof of concept. But the folks at Knowledge Media Institute are asking the right questions about the future of presence, and as such BuddySpace bears watching.

Kevin Reichard is executive editor of InstantMessagingPlanet.