Pidgin is the successor of the popular Instant Messenger (IM) client Gaim. It supports more than a dozen protocols and allows you to use several of your IM accounts on those systems simultaneously. Pidgin is compatible with IM systems AIM, Bonjour, Gadu-Gadu, Groupwise, ICQ, IRC, MSN, QQ, SILC, SIMPLE, Sametime, XMPP, Yahoo!, and Zephyr.
The latest release features a new and improved conversation window and formatting toolbar. Since version 2.0.0 the core of the application, libpurple, has been completely separate from the user interfaces. Pidgin is a GTK+ user interface, whereas Finch uses ncurses, and Adium uses Cocoa.
Besides its core instant messaging functionality, Pidgin supports file transfer, away messages, typing notification, Buddy Pounces, plugins, spell checking, and tabbed conversations. It does not yet support voice or video chat.
Pidgin 2.0 can be downloaded as source code or as a pre-compiled Fedora Core package. For more information see here.
Pidgin not Pidgen
http://www.pidgin.im/