Internet Explorer zero-day exploit?

The folks over at The Sans Institute (Incidents.org) are reporting on a possible zero-day ( 0-day ) exploit against Microsoft Internet Explorer. (A zero day exploit is the name given to an exploit of a previously unknown vulnerability.) Their analysis essentially had the machine they were using go to 100% cpu and it did not give the claimed behavior. They're thinking this may just be an exploit of one of the other vulnerabilities disclosed Tuesday (MS05-038)

I wonder, if it is a zero-day if this would force MS to break out of their "once a month disclose and patch vulnerabilities" schedule. I would hope they're taking as close a look at this as SANS is.