From GeekNewsCentral:
Overnight, Microsoft issued a rare out-of-cycle patch for Windows systems that should be installed immediately. The vulnerability affects all versions of Windows and could have an impact similar to the 2003 Blaster Worm attack. If you’re not set to auto-update, be sure to go out and grab the update.
Now like the author of that post, my machines are set to auto-update in the early morning. However, I like to run update manually sometimes just to make sure. Not every one does though, so if you have a less-geeky friend or family member – remind them to update! I know it never works, but it is worth a try. (First thing I do when sitting at a persons computer to work on it is start running windows and virus scan updates.)