While I was on vacation last week, several of our No Jitter bloggers were busy explaining the role that presence plays in UC (see Zeus Kerravala and Irwin Lazar). Among other points, Zeus notes that UC and presence don't necessarily require ubiquitous VoIP deployment, and he points out that presence could someday extend beyond individuals and their communications devices; potentially, any device that can be communications-enabled, such as a computerized production line device, could be presence-enabled for status tracking.
In his piece, Irwin notes the critical role that organizational challenges will play in getting presence deployed in the enterprise. Since presence is the foundation for integrating business apps, communications apps, and the underlying network, the IT staff responsible for all these elements must cooperate closely to achieve the integration.
Another enormous challenge to presence-enablement is a fundamental UC challenge that I discussed early in the life of this blog: Interoperability. Obviously, the more endpoints you can presence-enable, the more valuable presence becomes; it's a basic network effect at work. But at the same time, the more endpoints you're seeking to presence-enable, the more likely it is that they rely on different vendors, whose systems very likely do not implement the critical standards in an interoperable manner (Irwin touches on the importance of standards in his NJ post as well.) Furthermore, the process of linking different vendors' presence systems, if you are in a multivendor environment, has some inherent challenges that the vendors will have a difficult time overcoming even if they're inclined to try to do so. I wrote a feature on No Jitter that gets into some of the gory details.
So presence is a big step forward conceptually, as it helps us get a clear idea of what Unified Communications is, holistically. The bad news is, actually implementing presence in a true UC architecture is going to be a major challenge.