Combine sugar and water in a medium sauce-pan; bring to a boil, stirring until sugar dissolves. Pour sugar mixture into a 4-1/2 quart freezer container. Stir in fruit juice; freeze until firm. Remove from freezer several hours before serving (mixture should be slushy). Stir in ginger ale. Garnish with pineapple wedges, if desired. Yield: 5-1/2 quarts.