I really like XMPP for IM and pretty much everything now. But IRC is no problem, I am sure there is an XMPP to IRC gateway so it would still work just as smoothly as everything else does in it.
So if you want to set up something just pick a channel and server on IRC and I will add it on pidgin or somewhere and if nothing else I'll idle in there to help your numbers
We need a bot to announce new topics from the site onto the channel. That could be cool and make a good reason to hang around in there.