Windows 8 To Revamp Windows Update
 

Microsoft says it is improving the automatic update process in Windows 8 and, among other things, is minimizing the amount of restarts needed during an update. The obvious question to ask first is why does the installation of updates even require a restart at all? Ideally, we would like all update installations to happen seamlessly in the background without a restart. But, in reality, there are situations where the installer is not able to update files because they are in use. In these cases, we need to restart your machine to complete the installation. The automatic updating experience thus needs to be able to handle cases where restarts are required.

http://www.hardocp.com/news/2011/11/...revamp_update/