IRC is an acronym that stands for "Internet Relay Chat", which is kind of like IM except more community-oriented: People set up "rooms" nominally dedicated to particular subjects, and you generally join one or more of these "rooms" and converse as you would in a "real-life" room containing a small number of casual acquaintances – only without accidentally "talking over" anyone or having to say "sorry, could you repeat that?".
We have an official channel for ourselves and a few friends (although we belong to many others); it is listed on the contact page. Feel free to drop by.
Eventually, we plan to have a web-based client set up, so we can just direct people to a web page if they don't have an IRC client installed.