Open source, easy-to-use XMPP messenger: Open-IM
quite a while ago, I started this Project and after a few rewrites I think it's reaches a status in which it can be used ;)
It's name is Open-IM and it's supposed to be an open-source instant messenger. It uses XMPP (specifically the loudmouth library) and GTK+ for its user interface. The goals are to keep the messenger easy in usage and to spread the usage of XMPP and encrypted instant-messaging. Also, one significant advantage over proprietary networks like ICQ is, that Open-IM doesn't log whatsoever. This might make it attractive for privacy-concerned people :)
Open-IM is released under the terms of the GNU GPLv3.
The Project website is http://www.open-im.org. Available for download are the sourcecode for compiling on Linux and other Unix flavours and an installer for Windows (32 Bit). It's tested and runs fine on Windows XP. Vista compatiblity was not tested yet.
There are also packages for debian GNU/Linux (and other debian-based distros like ubuntu), but they are not the most recent ones. I'll build recent ones this evening.
As soon as I find out how, I'll also deliver packages for RedHat and other rpm-based distros ;)
On the website are also screenshots (if you're curious) and a manual for novice users or those who need help compiling or installing Open-IM.
Note: Open-IM is not to be confused with OpenIM (the XMPP server). Sorry, by the time I realised, the domain was already rented... :)