First, a little fun. I found this survey asking just that question, but in a humorous way. Here are the results, which were presented at the Agile 2008 conference in Toronto. I also found (through LinkedIn) a post on Peter DeYoe’s blog with a humorous job posting for a Scrum Master.
Now for a real live case study. In my job hunting, I discovered this article by Damon Pool on Litle & Co. The reason I like this story so much is that not only did the push for Agile come from the top, but they started out that way. They didn’t adopt Agile, they were born with it. That eliminates a lot of problems that come along with trying to adopt Agile later on: