I still have not seen the Win7 Platform Update listed in Windows Update and now I know why. It is installed as part of the IE10 upgrade. I was wondering what it meant while the installation of IE10 was running when it said that necessary updates were being downloaded and then applied. From a Google search it is evident that it was the platform updates that got applied. I can't find any information about which files get updated by the platform update so I could check and confirm that it did in fact occur.