Kadu is a Polish open-source IM client. Currently (version 0.6.5) it supports only proprietary Gadu-Gadu protocol, but in next version the Jabber XMPP will be also supported. We (the Kadu Team) are planning to make the best IM on the world ;)
And we have the power to really do it - Kadu in Poland is most popular Linux Gadu-Gadu client, and many of our users will use it instead of Psi when it gains XMPP support. We will have QGraphicsView-based contact list, Phonon-based multimedia support. We have chat dialog with full HTML and CSS support (thanks to WebKit), Kadu is the most configurable IM client out here - and the configuration dialog is really very convienant. We have our own usability team that work on upcoming 0.6.6 and 0.7 user interface.
We have support for plugins (called modules) and a lot of users that write their own modules - it is one of the reason Kadu is so popular (imagine kadupanel module that turns the window into hideable panel just like Kicker in KDE 3.5, or screenshot module that allows sending images of part of the screen directly in chat).
Some words about myself: my name is Rafał Malinowski, I'm a programmer from Poland and I'm working on Kadu project. I'm also working for Cognifide Poland, where I'm writing ASP.NET internet pages (like Setanta).
I'm going to write more about Kadu in this blog, to promote it and to improve my english and general writing skills ;)
I hope you will enjoy reading this blog.