I am glad DHH has put up this piece. This is one of my favorite topics to be contrarian about. I am a strong believer in the importance of developer testing to ensure code quality, but some people take it way too far. I gave a talk about this at RubyFringe: http://railspikes.com/2008/7/11/testing-is-overrated

I also am utterly opposed to the Cucumber-style programming-in-English-via-regexp testing approach. Unless someone who doesn't know how to code is writing those step files, why subject yourself to that?!