Depending upon the time of day (seems to be at its worst in the morning here in the UK), I'm seeing delays of up to an hour when pausing or resuming ad groups (ie I pause an ad group but still see the ads an hour later, with the Ad Diagnostic Tool also telling me the ads are still running).
Seeing this more and more frequently.
I was talking about the displaying of ads (or switching off of ads) being delayed by increasingly large amounts of time, usually soon after 8am for up to 2 hours (which, probably not coincidentally, is when Adwords switches into a new day - presume there are some background processes running that are causing this?)