Pidgin is an instant messaging program for Windows, Linux, BSD, and other Unixes. You can talk to your friends using AIM, ICQ, Jabber/XMPP, MSN Messenger, Yahoo!, Bonjour, Gadu-Gadu, IRC, Novell GroupWise Messenger, QQ, Lotus Sametime, SILC, SIMPLE, and Zephyr.

Pidgin can log in to multiple accounts on multiple IM networks simultaneously. This means that you can be chatting with friends on AIM, talking to a friend on Yahoo Messenger, and sitting in an IRC channel all at the same time.
Pidgin supports many features of the various networks, such as file transfer, away messages, and typing notification. It also goes beyond that and provides many unique features. A few popular features are Buddy Pounces, which give the ability to notify you, send a message, play a sound, or run a program when a specific buddy goes away, signs online, or returns from idle; and plugins, consisting of text replacement, a buddy ticker, extended message notification, iconify on away, spell checking, tabbed conversations, and more.

version 2.3.1 (12/7/2007):
http://developer.pidgin.im/query?status=closed&milestone=2.3.1
NOTE: Due to the way this release was made, it is possible that bugs marked as fixed in 2.3.1 will not be fixed until the next release.

libpurple:
* Fixed a number of MSN bugs introduced in 2.3.0, resolving problems connecting to MSN and random local display name changes
* Going idle on MySpaceIM will no longer clear your status and message.
* Idle MySpaceIM buddies should now appear online at login.
* Fixed crashes in XMPP when discovering a client's capabilities
* Don't set the current tune title if it's NULL (XMPP/Google Talk)
* Don't allow buddies to be manually added to Bonjour
* Don't advertise IPv6 on Bonjour because we don't support it
* Compile fixes for FreeBSD and Solaris
* Update QQ client version so some accounts can connect again
* Do not allow ISON requests to stack in IRC, preventing flooding IRC servers when temporary network outages are restored
* Plug several leaks in the perl plugin loader