In a large saucepan, combine the first 5 ingredients. Bring to a boil. Reduce heat; simmer, uncovered, 4-6 minutes or until cranberries are softened. Remove from heat; cool slightly. Transfer to a blender; process until smooth. If desired, strain through a fine-mesh strainer. Pour into a 6-cup ring mold. Freeze until solid.
Just before serving, wrap bottom of mold in a hot damp dishcloth; invert onto a baking sheet and lift off mold. Place ice ring in punch bowl. Gently stir in ginger ale, cold water, pineapple juice and lemon juice. If desired, serve with mint leaves and additional cranberries.