Light a grill. In a bowl, toss the nectarines with the sugar, cinnamon and 1/2 of the gingersnaps. Spoon 1/4 tablespoon of the butter in the center of each sheet of foil and top with the fruit. Bring 2 sides of the foil up over the fruit and fold to form a seam across the top. Fold the remaining 2 sides to seal the hobo packs completely.