Microsoft Advance Security Notification Changes (January 8, 2015)

Microsoft will no longer provide advance notification about its monthly security bulletins to the general public. Instead, the information will be available only to paying Premier support customers and to organizations that participate in the company's security programs. The service, which began more than a decade ago, provided information about bulletins on the Thursday prior to the patches' Tuesday release. Microsoft has said that the main reason for the change is that most customers no longer use the information available in advance.

More:
http://www.zdnet.com/article/microsofts-advance-security-notification-service-no-longer-publicly-available/
http://www.computerworld.com/article/2866996/microsoft-abruptly-dumps-public-patch-tuesday-alerts.html
http://blogs.technet.com/b/msrc/archive/2015/01/07/evolving-advance-notification-service-ans-in-2015.aspx