Gaim v1.5 is a multi-protocol instant messaging (IM) client for Linux, BSD, MacOS X, and Windows. It is compatible with AIM and ICQ (Oscar protocol), MSN Messenger, Yahoo!, IRC, Jabber, Gadu-Gadu, SILC, GroupWise Messenger, and Zephyr networks.
Gaim users can log in to multiple accounts on multiple IM networks simultaneously. This means that you can be chatting with friends on AOL Instant Messenger, talking to a friend on Yahoo Messenger, and sitting in an IRC channel all at the same time. By using tabs for multiple conversations the user's desktop stays organized, instead of having separate windows all over. When a new message is received that tab name turns bright. A great feature.
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Gaim runs on a number of platforms, including Windows, Linux, and Qtopia (Sharp Zaurus and iPaq). Gaim integrates well with GNOME 2 and KDE 3.1's system tray, as well as Windows's own system tray. This allows you to work with Gaim without requiring the buddy list window to be up at all times. Gaim is under constant development, and releases are usually frequent. The latest news regarding Gaim can be found on the news page.
You can download Gaim at: http://gaim.sourceforge.net/