Scott Ambler gave this excellent presentation as part of Agile 2008 Conference last week, debunking a variety of assumptions, myths and a misconceptions surrounding Agile. Most discussion is based on field data gleaned from a large-sample survey distributed among the agile community intended to find out what is actually happening in the industry, not what should be happening (in an ideal agile environment). I found this interesting because generally, Agile is discussed in context to the latter, which I think causes some people to focus too much on being Agile while loosing sight of it's original intention - producing better products in more efficient ways.
Scott does a good job of analysing the various responses from different areas (management, development, project managers, design) and discussing what may cause some of the much-discussed tension between these groups.
By the end it's clear - common sense prevails, and 'successful' agile teams adopt the most appropriate techniques that help them deliver better products within the constraints of their environment. These are not necessarily the same techniques that Agile evangelists preach from scrum-master pedestals.