I read that Trillian supports the XMPP Conference feature and there is supposed to be a "Join a Conference" option when I click my account icon. But when I click my Gmail icon, I don't see it. I thought Gmail Talk supports XMPP. Why doesn't it show up?
You have to create a separate XMPP account in the Trillian account manager, with the same Gmail email address and password. Then, click the V (XMPP icon) then Join a Conference.
Even though Gmail Talk uses XMPP, Trillian does not expose this functionality through a "Gmail" account.