In a probably related announcement, Facebook and AOL/AIM have announced some sort of "partnership" "that will integrate a user's Facebook friends into their AOL Instant Messager". What I suspect that means is that AIM is simply running an XMPP client in the AIM server software, and is using "Facebook Connect authentication (X-FACEBOOK-PLATFORM)" as described here.
This is not nearly as exciting or useful as the Facebook/XMPP thing. It works in the wrong direction to be useful to me. I would still have to run a local AIM client. I'm already running an XMPP client, and now I can use that to chat with Facebook users.
What AOL/AIM should do is do what Facebook just did. Set up their own XMPP server and gateway. Then they don't need their "partnerships" with Facebook or with Google Talk. Just turn on S2S peering, and email@example.com, firstname.lastname@example.org, and email@example.com can Jabber away to each other to their heart's content. Harry wouldn't even need to stop using his old AIM binary, while Tom is using his Android phone, and Dick is puttering around on the Facebook web page.