I attended the Scott Robertson workshop in LA on Rendering Reflective Surfaces. It was an outstanding workshop, I learned tons, and am still processing it all. I do want to point out that he is also teaching a longer class on the subject over at schoolism.com ! http://schoolism.com/school.php?id=20
Go check it out! It's not often you get to learn from one of the masters of concept art.
If you are in LA or willing to travel then also check out his workshops page: