Error message displayed in the Update pane of SBS console:
"Update Services is not properly installed. The following or one of its dependencies is missing: Microsoft.UpdateServices.A
ion, Version=3.1.600.1.1, Culture=neutral, PublicKeyToken=316f3856ad3
The original updater that installed with SBS ran fine for several iterations. Eventually, it was time to install the latest WSUS package.
This error occurred while running the normal update process on a clean install of SBS 2008.
This error occurred when it attempted to install the WSUS SP. Predictably enough, the installer failed "gracefully" by rolling back the install but NOT rolling back to the uninstall of the prior version.
The attached file is the complete log written at the time of failure.
A solution which does not require reinstalling SBS is certainly worth 500 points to this member!