You can see if people are hanging out in the #boo channels:
GimpNet network: irc://irc.gimp.org/boo
Codehaus server: irc://irc.codehaus.org/boo
If no one is there, please try the Mailing Lists.
There are related IRC channels for #mono and #c#.
There are many popular IRC clients out there.
On Linux there are clients like Gaim, XChat, BitchX.
On Windows there is Gaim, Trillian, X-Chat, mIRC.
If you are interested in accessing IRC from a boo script, check out IRC libraries like SmartIrc4net (used by Gnosmirc) or Thresher.