Lightly grease one side of a large sheet of aluminum foil. Place salmon on the greased side of foil. Melt the butter in a saucepan over medium heat. Remove from heat, and mix in cilantro and jalapeno. When cilantro is wilted, drizzle butter mixture over the salmon.
Place foil with salmon on the grill. Season with Old Bay. Cook 15 minutes, or until fish is easily flaked with a fork.