I use foil on everything. I'm foiling two ribeyes as I write (only for 5 minutes). Butts, Brisket, ribs (when I have guests who want fall off the bone), I even let my chicken rest under a little foil for a few minutes.
EDIT: Maybe I misunderstood the question. If you're referring to foiling while cooking I recently did my first foiled brisket and in my case was pleased with the results. As I said above if my guests are wanting fall off the bone ribs I'll foil their ribs. Other than that, all my foile is applied after the cook.