For the time being, we have an open IRC server setup at irc.onetendev.com - You can connect to it using any IRC capable client, of which there are many. Here are a few that we use…
Pidgin (formerly Gaim) - cross-platform, multi-protocol (AIM, GTalk, IRC, ...)
Colloquy - Mac-only, simple and user-friendly.
HydraIRC - Windows-only, full-featured.
See en.wikipedia.org/wiki/Comparison_of_IRC_clients for more options. When you connect to the server, you should be able to get a room/channel list and see where people are. Currently we are using the #raclin channel.
Hop in and say hello! It could be a good congregating place for some geeky discussions about presence and technology.
IRC for FireFox
Of course, you can just piggyback on your favorite browser. I have ChatZilla installed as a FireFox extension and I like it.