I prefer pidgin as my instant messanger. It is much easier to use, and much more stable ( in my expierences) than miranda. Miranda is much more customizable, but it frequently crashes for me. I was on the pidgin website the other day (www.pidgin.im) and one of the posts discussed using adium message styles in pidgin. The developer said he got a stable version working within a couple of hours and even provided a file to download. However the file is a c file and i have no idea what to do with it. i know that there alot of good developers here who could probably get this working easily, so I am asking anyone who wants to take on this project to please do their best to get it working, and I would thank you tenfold! The discussion of pidgins website can be found here: http://planet.pidgin.im/ if you scroll down a little ways.
Attached is a screnshot from the pidgin website of pidgin using the "glass" adium style

Aqua-Soft Forums