ScatterChat is a secure instant messenging program which supports all major chat networks, second generation onion routing for anonymization, as well as end-to-end encryption for both chat and file transfers.

http://www.scatterchat.com/

It is a secure instant messaging client (based upon the Gaim software) that provides end-to-end encryption, integrated onion-routing with Tor, secure file transfers, and easy-to-read documentation.

Its security features include resiliency against partial compromise through perfect forward secrecy, immunity from replay attacks, and limited resistance to traffic analysis... all reinforced through a pro-actively secure design.

In my testing - unreliable.  Simple UI things like having the messenger minimize to the tray are not enabled by default (the plugin has to be enabled) and I experienced strange disconnects - and random inabilities to reconnect.

The GUI was smooth - for the most part - but not polished.  The icons were huge - so my contact list goes on for pages... and there's no way to resize these icons from the provided configuration options.

There's inconsistent update notification - the GAIM plugin for updates tells me I'm running an old version, while the ScatterChat launcher tells me I'm running the latest version.

I had about 5 crashes after 8 hours of testing.

A future release will probably address these issues and more - in the meantime, I'm going back to my horribly insecure client - because it means I can use my IM again.  Do you remember that feeling?  After you switched off the bloated AOL ICQ client (official) to Miranda ICQ or Trillian?  That huge burden of bloat lifted from your shoulders? My switch back to the generic MSN client was a breath of fresh air after using ScatterChat for a day.  I appreciate the security and the proper application design, as they claim - but the impact on productivity was far too great for me.  And I don't feel I need to give up that much functionality and performance for security.  At least - not yet.