Screaming Penguin - Source Does Matter

I think this is an *excellent* paper about software development practices in general: Scrum and XP from the Trenches. (Note: you may have already seen this, it's pretty old, but I just crawled out from under the rock and noticed it.)

Yes, it has a scrum focus, but it also discusses XP techniques and covers the entire spectrum in practical "this is what we found" terms. Props to Henrik.