Internet Relay Chat (IRC) is an instant messaging system focused around topics rather than people, and requires no registration.
There's almost always people hanging out on IRC for the conference, at server: irc.freenode.net, channel #recentchangescamp
If you don't already know about IRC, the easiest thing to do is to click here: http://www.mibbit.com/ and enter this information:
Downloadable IRC software is a little more complicated, but has more features. Some recommendations for different systems:
If you want help figuring out how to use IRC feel free to post a question here, or check out some documentation yourself: http://www.irchelp.org/irchelp/
You may be able to just click here: irc://irc.freenode.net#recentchangescamp (for Chatzilla and some other systems)