Well, I actually had two hats complete, threw them into the washer, then dryer. Guess what? When you forget to label your balls of yarn, it's very easy to mix superwash wool and regular wool. What happened? You got it! They felted!
One is still definately usable, but the other shrunk differently and now will only be good as a felted bowl. I'll be working on a new one in the morning.