A nice article by Alex from 2007: <a href="http://thedailywtf.com/Articles/The-Great-Pyramid-of-Agile.aspx" rel="nofollow">http://thedailywtf.com/Articles/The-Great-Pyramid-of-Agile.a...</a>
In particular, I like this sentence: "a simple, painful truth: you have to know what to build before you can start building it."