I guess it'd be a feature added based on demand and usability.

In the past, we've had the tendency to sometimes cram our SMF forums with all sorts of gadgets/widgets and modification packages.
We probably don't want to overload it with things that are unnecessary and/or of little use to the wide forum base.
Think there are quite a few people suggesting ideas such as a chat system. We had tried out Ajax Chat some months ago, and I think that was a useful way of communicating in groups, holding meetings etc. It was particularly useful as it was integrated with the forum and could create"rooms" based on the boards present - allowing people with the right rank (membergroup) and access levels to see them.
Ajax wasn't always the most stable. I suppose, once these new forums settle down (I think there's a decent amount yet to patch up) the community heads would be thinking about features such as this.