The Pidgin open source instant messaging client is out with its latest release version 2.4.0.  Pidgin is the project that was formerly known as Gaim and is widely deployed on both open source and Windows platforms.

Pidgin is what's known as a multi-headed IM client with support for AIM, ICQ, Jabber/XMPP, MSN Messenger, Yahoo!, Bonjour, Gadu-Gadu, IRC, Novell GroupWise Messenger, QQ, Lotus Sametime, SILC, SIMPLE, MySpaceIM, and Zephyr.

With 2.4.0 Pidgin users gain a few key features that they've been lacking for years. Among them is the ability to have offline messaging for AIM accounts.  Pidgin/Gaim has had the ability to do offline messaging with Yahoo accounts for a while but AIM offline messaging support is a new thing that many users have been asking for.

Pidgin 2.4.0 also now provides support for Yahoo! Messenger 7.0+ file transfer method, so Pidgin users can now send files to their Yahoo! messenger buddies.

The 2.x branch of Pidgin is barely a year old at this point, but it seem to me that in the last few months it has finally hit its stride with regular updates for features and bug fixes.

While Pidgin is an open source project, it is lead by  Google staffer Sean Egan , so at one point there was a lot of speculation that Google would be calling the shots on this project. As it turns out that apparently never really became the case and Pidgin continues to fly on its own path.