Well, i just all the literature for my driving class on May 6th. This class is put on by BMWCCA, so I suspect I am going to spend most of my time on the track staying out of the way of all those M3's :-(
Anyway, one of the recommendations they make is to run 20w-50 oil at the track, and change the oil before and after the track day. They claim the oil breakdown and foaming can be quite severe.
Also, they sent me a great paper on how to drive Second Creek (a corner by corner description), for both clockwise and counter-clockwise running. Very useful.
So I'll let you all know what I think of the class after it's done. BMWCCA puts on this class every year, and it came highly recommended.
--Bob