An update is available for all Microsoft products that use Active Directory Rights Management Services (AD RMS) or Windows Rights Management Services (RMS). This update prevents you from receiving error messages that are related to the application manifest expiry feature of AD RMS or RMS clients and server applications. Specifically, all client and server AD RMS-aware/RMS-aware applications need to have this update installed. The update does not affect the AD RMS/RMS servers.
This update is particularly important for AD RMS customers using Internet Explorer, because the certificate for the RMA add-on for Internet Explorer will expire on February 22nd. The RMA add-on for Internet Explorer allows users to view content with restricted permission in Internet Explorer. It is critical that these customers install the update before then, in order to avoid any issues accessing or protecting web-based content.
For more details, you can read the recent blog post on the Microsoft Forefront team blog.
If you download and install this AD RMS client update, the update built specifically for Microsoft Office applications (released on December 11, 2009) is not required.