title: Rails respond_with: how does it work?
body: <p>I've been reading here and there about how cool the <code>respond_with</code> method is in Rails 3. But I can't even find a reference to it in either the Rails APIs or by searching the source. Can anyone either explain to me how it works (what options you can use, etc) or point me to the place it's actually implemented so I can peruse the code on my own?</p>