For this month, the company has announced that it will release one security bulletin on November 9. According to the Web page where advance notices are now posted , the bulletin and patch are related to Microsoft Internet Security and Acceleration (ISA) Server. The advanvce notice indicates that the "greatest maximum severity rating for this security update is Important. This security update may require a restart."
Microsoft also posts a caveat with the advance notices which states that the "information contained in this notification is subject to change due to the complexity of testing security updates. Therefore, the notification should not be viewed as definitive."
Starting in December you'll be able to sign up for advance notices via email. Check the Advance Notice Web site next month for details.