Thought I would just share...
/DetectNow - request the Windows Update Agent to do a scan
/ReportNow - when using this, use it in combination with /DetectNow, so wuauclt.exe /DetectNow /ReportNow to get the Windows Update Agent to scan and send the reporting events to the WSUS mothership
/RunHandlerComServer
/RunStoreAsComServer
/ShowSettingsDialog - invokes the CPL UI for the current AU settings
/ResetAuthorization - resets the authorization cookie
/ResetEULAs - resets the EULA that have been accepted?
/ShowWU - shows the Windows Update page or CPL (in Vista or later)
/ShowWindowsUpdate - shows the Windows Update page or CPL (in Vista or later)
/UpdateNow - seems like it wants to start a download and install if configured otherwise you see this...
2009-10-01 08:08:50:695 1428 e7c Misc =========== Logging initialized (build: 7.2.6001.788, tz: -0500) ===========
2009-10-01 08:08:50:695 1428 e7c Misc = Process: C:\Windows\system32\wuauclt.exe
2009-10-01 08:08:50:695 1428 e7c Misc = Module: C:\Windows\system32\wucltux.dll
2009-10-01 08:08:50:695 1428 e7c CltUI AU client got new directive = 'Download Approval', serviceId = {3DA21691-E39D-4DA6-8A4B-B43877BCB1B7}, return = 0
2009-10-01 08:10:35:220 1088 1248 AU Can not call UpdateNow if AU is not configured for auto download)
2009-10-01 08:10:35:220 1088 1248 AU WARNING: UpdateNow failed with hr:80070005
/DemoUI -shows the shield for WU and pops the balloon