Apparently there has been another worm running (crawling?) around and I missed it. This is what happens when I give up Slashdot. Anyway, one of them got loose inside an instant-messaging network provided to Reuters customers, according to the article Reuters Recovers From Kelvir:
DeSouza also called any link between Thursday's attack and other events this week -- including the disclosure of an MSN Messenger vulnerability by Microsoft and the announcement by America Online that it would make its network accessible to users of several other IM clients, including the open-source Jabber -- just coincidence.

They had nothing to do with this, he said. It was just another Kelvir.
Here's my actual transcript of the press conference. [NOTE - fictionalized. In other words, I wasn't there.]

DE SOUZA: Yes, question in the back.
REPORTER: (inaudible)
DE SOUZA: Could you repeat that?
REPORTER: Was this attack related to the newly-announced vulnerability in MSN Messenger?
DE SOUZA: No, the Kelvir worm exploits an older vulnerability, and has been for about six weeks now. Hello! (Laughter) The timing was just a coincidence. Other questions? Yes.
REPORTER 2: America Online has promised to open its network to other IM clients, including Jabber. Is it possible that this attack was a publicity stunt by AOL?
DE SOUZA: Sheesh. They had nothing to do with this. It was just another Kelvir.

Life is more fun in fictionalized mode!