secure Instant Messaging systems as MSN, Jabber, etc

Today I was wondering if It would feasible to use any plug-in in your
current favourite IM tool for securing and encrypting your conversations.

After some short research on the Internet I found this website about
SIMP project:

http://www.secway.fr/us/products/all.php#

Their product are not GPLed licenced, but seems promising, since you
could add encrypting capabilities using their free edition to any your
favourite IM tool: MSN, Jabber, Yahoo, Google, etc.

Also the possibility of encrypting under Unix, for instance setting up
in your linux router a software that automatically encrypts all your IM
conversations.

I find it interesting and I probably will check it when I have time, one
of my numerous ToDOs :)

Have a nice day