Cut salmon fillet into 4 serving pieces; remove any small bones.
Peel 1 grapefruit; cut into segments between membranes; set aside. From remaining grapefruit, squeeze enough juice to measure 1/4 cup.
In 1-quart saucepan over medium-high heat, heat red wine to boiling. Cook wine until reduced by half, 3 to 4 minutes. Stir in grapefruit juice, sugar and 1/4 tsp salt; keep sauce warm.
In cup, mix oil, dried thyme, pepper and 1/2 tsp salt. Spray rack in broiling pan with nonstick spray. Place salmon pieces, skin-side up, on rack. With broiling pan at closest position to source of heat, broil salmon 3 minutes. Turn salmon and brush with oil mixture. Broil 5 minutes longer or until fish flakes easily with a fork.
To serve, place 1 piece of salmon on each of 4 warm dinner plates. Spoon grapefruit sauce over; garnish with grapefruit segments and fresh thyme. Makes 4 servings.