SecuriTeam has a post up that clears up a lot of the questions about the emergency patch released on Thursday. Why you should update, what active worms are exploiting this, and information about files that may be infected (or part of the exploit).
I urge you to check this site out for more pertinent information about this and other vulnerabilities.
Thanks to the Internet Storm Center for posting about this in their daily diary.
Have a great day:)