I've been using trillian myself. Does that work with AOL's native IM prog or just the standalone version? Looks like just the standalone 5.2+ client.
Also, looks like they just use one certificate, so, it appears that someone could get that program, and use a sniffer and still decode your conversations since the certificate (and it's password at least) are known. So the author mentions that it only helps a tiny bit... and I'd agree. Guess it depends on how paranoid you are.
Trillians encryption seems to be encoded for each session but I really don't know if it's better/worse.
Certainly any option is better than plain text.