In his latest blog entry, Jeff Sutherland introduces an attractive and exceptionally concise introduction to the Scrum development process, titled "Scrum in Five Minutes." Created by Swedish consulting firm Softhouse, this 16-page PDF file gives a brief outline of the pieces and players of Scrum.
[excerpt from Scrum in Five Minutes by Softhouse]
For those who are new to Scrum, such executive summaries can serve as a useful introduction.
In addition, short summaries like this can facilitate comparisons between the various flavors of agile development. Some others available are visual roadmap of Extreme Programming and What does Lean Software Development Really Boil Down To?