When cooking beer-can chicken, is there any danger that the paint will contaminate the chicken? How about the aluminum?

No. The paint (actually edible food dyes) is applied to the can at between 500° and 600°F. The can stays around 212°F when you cook a beer-can chicken on it—a much lower temperature than would be needed to melt the paint. Ditto with the aluminum. (And incidentally, aluminum occurs naturally in small quantities in most of the foods we eat.) We did a lot of laboratory testing to make sure the aluminum and paint stay on the can, not in the bird. The recipe for beer-can chicken is perfectly safe.