Ok we have PM service here but IMO that service sux. I was wondering if we would be having instant messaging coming with the new site format whenever that does come. It would be nice to shoot quick messages back and forth to people that are online instead of sending a PM and then having to refresh your browser a bunch of times waiting for a response.
Most forums don't have IM systems built-in, due to the bandwidth constraints. It might be worth looking into maybe adding a shoutbox type of add-in, but as far as I know nothing different in the way of PM features are rolling out with the new platform.
Shoutboxes are extremely heavy bandwidth users. Even if you do have one, you have to ensure it is very well written because a problem with the code can cause it to suck even more bandwidth. A person I know runs a site that normally uses 1.5TB of bandwidth a month. An issue with the shoutbox made that 30TB last month. He killed it very quickly when he saw the stats
I think a better option would be an IRC channel, but then you need people to monitor it and that is much more difficult than monitoring a forum.