SQL Server 2008 R2 SP1, available on the Microsoft Download Center since July 12th, is now available through Microsoft Update. The primary packages for SQL Server 2008 R2 SP1 will update systems with Standard, Workgroup, Developer and Enterprise editions installed.
For customers looking to upgrade their SQL Server 2008 R2 installations through Microsoft update, please point your browser to http://update.microsoft.com/microsoftupdate/v6/default.aspx and perform a "Custom" scan as Service Pack 1 is an optional update. The SP1 packages will be offered for each language and platform supported. Theses updates will also be available through Windows Software Update Services (WSUS).
Abhishek SinhaProgram ManagerSQL Server Sustained Engineering