As I noted some time ago, there is a standard series of announcements that are sent out when a server is undergoing planned (or unplanned) maintenance. And since these are official announcements, the authors want to sound official.
One way of sounding official is to give the times during which the outage will take place is a very formal manner. "The servers will be unavailable on Saturday, March 17, 2012 from 1:00 AM to 9:00 AM Pacific Standard Time."
Did you notice something funny about that announcement?
On March 17, 2012, most of the United States will not be on Standard Time. They will be on Daylight Time. (The switchover takes place this weekend.)¹
I sent mail to the "If you have questions, please contact X" address to confirm that they are indeed taking the server down from 1am to 9am Pacific Standard Time (i.e., from 2am to 10am Pacific Daylight Time), pointing out that on March 17th, most of the United States won't be using Standard Time. (I was planning on coming to work, but if the servers won't be back up until 10am, I can sleep in.)
The response I got back was "The machines will be unavailable from 1am to 9am local time."
So in fact when they wrote Pacific Standard Time, they didn't mean Pacific Standard Time. They really meant Pacific Time, but we'll stick the word Standard in there because it makes us sound all official-like. In other words, "We're using words not for what they mean but for how they sound." I'm surprised they didn't use military time, just to sound that much more awesome.
Bonus chatter: Not to be outdone, another announcement said that a particular server would be available from time X to time Y PDT, even though the United States was on standard time. So now I'm not sure what the logic is. Maybe they just pick a time zone randomly.
Tip to people who write these announcements: Just say "Pacific Time" or "Redmond local time".