Heat gas or charcoal grill. Cut 4 (18x12-inch) sheets of heavy-duty foil. Place each ear of corn on center of 1 foil sheet. In small bowl, mix herb butter ingredients. Brush or spoon herb butter over surface of each ear. Bring up 2 sides of foil so edges meet. Seal edges, making tight 1/2-inch fold; fold again, allowing space for heat circulation and expansion.
Place wrapped corn on grill over medium heat. Cook 15 to 20 minutes, turning occasionally, until tender. Open foil carefully to allow hot steam to escape. Drizzle corn with any remaining herb butter.