The network is Freenode (chat.freenode.net), while our room is #boingboing.
To connect you'll need an "IRC Client," dozens of which are available for almost every computing platform, including mIRC, Trillian, and X-Chat 2 for Windows; X-Chat Aqua and Colloquy on OS X; and IRSSI and other favorites on Linux and other UNIXish environments. You can also use the Chatzilla plug-in for Firefox or simply use the Freenode java applet to connect.
To register your nickname, which gives you the ability to send private messages and reserve your name from use by others, type "/msg NickServ register [choose a password]" when connected to the Freenode server. Don't share your password with anyone!
To wonder if IRC is an antiquated old protocol far past its prime, consider that Douglas Rushkoff was lamenting its death in '96. Boing Boing Gadgets loves to serve you Yesterday's Future Today!