Windows 7 / Windows Server 2008 R2 Service Pack 1 Revision Issue Resolved

A revision was made to the WSUS offering for Windows 7 / Window Server 2008 R2 Service Pack 1 (SP1) on 5/24 to address known installation issues. We are aware that this latest revision is incorrectly reporting as "Not Installed" for machines that have already installed the previous revision of the SP1 update. Also, if this revision is approved for installation, it will reoffer to machines that have already installed the previous revision of the SP1 update. Specifically

• Machines that have already installed SP1 do not need to reinstall this update
• Machines that have not yet installed SP1 can safely proceed with installing this revision of the update

This issue has been corrected with a revision released Tuesday, 5/31 at 10:00 a.m. Pacific Time. Please be sure to re-sync your servers to obtain the latest revisions and updates to these and other packages.

Source : http://blogs.technet.com/b/wsus/archive/2011/05/31/windows-7-windows-server-2008-r2-service-pack-1-revision-resolved.aspx