Nokia (the cell phone maker) uses Scrum. They have developed a test to check whether a team is really using Scrum or just doing what I call Cowboy Agile (see wikipedia on cowboy coding).
The Nokia Test is in two parts.
First, are you doing Iterative Development?
* Sprints must be timeboxed to less than 4 weeks (6 weeks to be iterative, 4 weeks for Scrum)
* Software must be tested and working at the end of a Sprint
* Sprints must start with an Agile specification
The next part of the test checks whether you are doing Scrum (in Nokia's opinion):
* You know who the product owner is
* There is a product backlog prioritized by business value
* The product backlog has estimates created by the team
* The team generates burndown charts and knows their velocity
* There are no project managers (or anyone else) disrupting the work of the team
This version is as slightly revised by Jeff Sutherland, based on the test originated with Bas Vodde at Nokia Siemens Networks.
Jeff Sutherland's experience from asking in numerous large meetings is that only about 10% of people will say they pass the whole test. He has since developed an alternate scoring approach to the test.
There could, of course, be a lot of discussion of this test. Should existing questions be changed? Should other things be added? How do you interpret each question? Etc. But it's a start.
You are welcome to discuss these issues on this wiki, or on Yahoo Scrum-Dev. Or review discussions already there. See also several blog posts (google Nokia Test).