I have heard about this company called MOVIT offering aftermarket ceramic brakes.
Official Website MOV'IT® - brakes, brake systems, braking systems:*ceramic brakes
I dont know much about them, but from what i understand, they are the most affordable.
Interesting on the Mclaren MP12 the steel brakes weight less than the Carbon. No one I know who serioulsy tracks runs carbon, esp the porche guys.
It doies have cool factor, and I can see how in an unlimited budget its going to offer atrack advantage in most cases, but youa re talking race teams. Cost aside they are just too fagile.