For those who haven't learned about SIMP (Secway's IM Encryption tool) you may want to check it out. They did update their Pro version to 2.20, which includes more supported IMs including GAIM, Trillian and a few others. They've also made the install GUI a little more user friendly (less screens). I've been using it successfully with friends to keep IM messages private for a couple of years now (initially on their lite version -- which is single IM client only -- and recently coughed up the $25 for the Pro version).

Anyways, FYI for anyone using the Pro version.