In case anybody is curious about Fire's partial AIM support it's because there are two AIM protocols.
One is called TOC, the other is called Oscar (I think). AOL let's people use the TOC protocol on any client. However, it's a lessor protocol that doesn't support direct connections or any of the things that a would require one (file transfer, voice, etc.).
Trillian has reverse engineered Oscar but their service sometimes drops as AOL figures out ways to kill trillian connections without hurting their own customers. I'm guessing that it's getting harder and harder to do that because trillian has been working well for months.
When Steve said that AOL let them "into the tent" it sounds like they are letting them use the Oscar protocol. The fact that they have file transfers further supports this guess.
Anyway, there's a little info for you.
Vanguard
PS My guess is that they aren't going to support other protocols because that might hurt their relationship with AOL.