We should review the contents of the MSDN document "Application Shutdown Changes in Windows Vista" (see URL) and consider updating our code with ShutdownBlockReasonCreate and friends. Yes, the real problem is god-awful shutdown times, but I have seen reports from users in the wild who are seeing "Well, this is embarrassing" messages when starting Firefox due to forced process termination during a previous Windows shutdown. At least presenting the user with some additional info could help them make an informed decision as to whether or not they should wait.
I see this all the time on my Surface book. We also continue to have problems where we spin the Windows event loop after receiving WM_ENDSESSION, which just kills the process outright. You're not allowed to do that AIUI.
Benjamin, moving to p2 per your request in email.