On Thursday (Mar 7) Microsoft announced the forthcoming content for Patch Tuesday – Mar 12, 2013.
You can have Microsoft's security bulletins sent directly to you:
To receive automatic notifications whenever Microsoft Security Bulletins are issued, subscribe to Microsoft Technical Security Notifications.
Microsoft also hosts a webcast where they discuss the releases, typically the Wednesday after Patch Tuesday:
Microsoft will host a webcast to address customer questions on the security bulletins on March 13, 2013, at 11:00 AM Pacific Time (US & Canada). Register now for the March Security Bulletin Webcast. After this date, this webcast is available on-demand.
You can also follow the MSRC team at @MSFTSecResponse.
Number of Releases: 7
Critical Security Updates: 4 addressing vulnerabilities in Windows, Internet Explorer, Silverlight v5, Office 2010, Visio 2010, and Sharepoint Server 2010.
Important Security Updates: 3 addressing vulnerabilities in Windows, OneNote 2010, and Office for Mac (2008 and 2011).
Updates are typically released by Microsoft at 10am PT (6pm UTC).
Configuring WSUS servers to synchronize relative to that time can be helpful in expediting availability of these security updates.