Responding to a pair of posts from ZDnet blogger Adrian Kingsley-Hughes detailing certain Windows system files being updated without notification or permission, Microsoft today issued a clarification on their Windows Update team blog:

One question we have been asked is why do we update the client code for Windows Update automatically if the customer did not opt into automatically installing updates without further notice?  The answer is simple: any user who chooses to use Windows Update either expected updates to be installed or to at least be notified that updates were available.  Had we failed to update the service automatically, users would not have been able to successfully check for updates and, in turn, users would not have had updates installed automatically or received expected notifications.

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The point of this explanation is not to suggest that we were as transparent as we could have been; to the contrary, people have told us that we should have been clearer on how Windows Update behaves when it updates itself. This is helpful and important feedback, and we are now looking at the best way to clarify WU’s behavior to customers so that they can more clearly understand how WU works.

In other words, Windows Update has to update itself in order notify you that there are Windows Updates available. You got that? Good.