Well murr-ello there! I've taken an interest in this idea, and think it will be a fantastic mini-project to flex my Trillian plugin muscles before I take on Second Life. I think the challenge will be incorporating all the F-Chat specific features, like mini-profiles and RP ads.
Feel free to contact to me on F-List if I'm ever online: Syldra Kitty
I'll try to remember to tell someone if I succeed.
[ An incorrect mention of Trillian not supporting plugins in the free version used to live here. Sorry if my misinformation misled anyone! ]