Great tidbit of insight from Kent Beck today at hack.summit():

Q: “Do you use TDD at Facebook? Is it always good to do TDD?”

Kent: “TDD is not always the best thing to use. Some of the things we’re doing at Facebook have never been done before… no one has used memory or code in these ways before. You don’t even know what the outcome is going to be, so how will you write a test for it? It’s not about being religious about a methodology. It’s about the feedback loop - the faster you can get that feedback, the better, whether you use TDD or not.