Co-incidentally I've just had to do this as well - I have an automatic server build process for my Citrix blade servers which builds them from bare disk, and I needed to ensure that they are up-to-date before they get released into the farm.

As with your solution it uses (our internal) WSUS servers to provide the authorised updates - the scripting is just to force the updates to happen immediately and to automate the multiple reboots and logins that are required.