It lets you connect on:
Gadu-Gadu (Polish instant messaging network)
AIM's TOC (it's AIM, only it goes over the text-only network that AIM uses for it's browser-based clients)
Plus it works on both Windows, Linux, Mac OS X, and Unix. It might take a little more effort installing on some operating systems though.
It's updated regularly, so they created a RSS feed to keep people up to date. It's update once a week, so your friends list won't be stuffed with pointless entries.
pidginnews - Keep up to date with the latest news about gaim and the messaging networks it uses.