* If you have not done so, configure the client workstations (both domain-joined and workgroup) to use the WSUS server (by using Group Policy or registry files)
* Enable Client SUP installation method in Site Database / Site Management / <site code> – <site name> / Site Settings / Client Installation Methods.
* Behind the scene, the Configuration Manager Client update bits get automatically approved in WSUS and then pushed to the client workstations.
* On the client machine, open c:\windows\WindowsUpdate.log and check for something simiar to the below (use the wuauclt /detectnow command to expedite the process)
2009-06-15 13:46:13:628 832 66c Agent ** START ** Agent: Installing updates [CallerId = AutomaticUpdates]
2009-06-15 13:46:13:628 832 66c Agent *********
2009-06-15 13:46:13:628 832 66c Agent * Updates to install = 1
2009-06-15 13:46:13:638 832 66c Agent * Title = Configuration Manager Client Installation
2009-06-15 13:46:13:638 832 66c Agent * UpdateId = {428DF9AD-10A9-4B6E-8FD1-6FBA23B41E22}.1
2009-06-15 13:46:15:013 832 66c DnldMgr Preparing update for install, updateId = {428DF9AD-10A9-4B6E-8FD1-6FBA23B41E22}.1.
* Fore more information, please visit: http://technet.microsoft.com/en-us/library/bb633194.aspx