SQL Server 2008 SP3, available on the Microsoft Download Center since October 6th is now available through Microsoft Update. The primary packages for SQL Server 2008 SP3 will update systems with Standard, Workgroup, Developer and Enterprise editions installed. For customers looking to upgrade their SQL Server 2008 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 3 is an optional update. The SP3 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
"The primary packages for SQL Server 2008 SP3 will update systems with Standard, Workgroup, Developer and Enterprise editions installed."
SQLServer2008SP3-KB2546951-x86-ENU.exe can also upgrade Express Edition components such as Database Engine and Basic Management Tools, isn't it?
Windows Update is also suggests installing this 305Megs update on SQL Server 2008 Express SP2.