One of the biggest lessons that any Adobe developer will tell you is "we're proud of the code and that it hasn't needed a rewrite - but if we were doing it from scratch we'd do it way different."

A great read on that conversation is http://blogs.adobe.com/jnack/2009/05/some_thoughts_about_the.... But I doubt anything insightful will come out of this leak along the same veins as we leaned when HL2 leaked.