1. To prepare compote, combine first 3 ingredients in a medium saucepan over medium-high heat; bring to a boil. Cover and simmer 25 minutes or until rhubarb is tender and mixture thickens, stirring occasionally. Remove from heat, and keep warm.
2. To prepare waffles, combine cornmeal and 1 cup boiling water in a large bowl. Let stand 20 minutes or until cooled to room temperature.
3. Coat a waffle iron with cooking spray; preheat.
4. Add eggs to cornmeal mixture; stir with a whisk to combine. Stir in butter, 2 teaspoons rind, and juice. Weigh or lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and next 4 ingredients (through baking soda) in a bowl; stir to combine. Add flour mixture to cornmeal mixture. Combine low-fat yogurt and milk in a bowl; stir with a whisk until smooth. Add yogurt mixture to cornmeal mixture, stirring just until combined.
5. Spoon about 1/4 cup batter per 4-inch waffle onto hot waffle iron, spreading batter to edges. Cook 3 to 5 minutes or until done; repeat procedure with remaining batter.
6. To prepare topping, combine Greek yogurt and remaining ingredients in a small bowl; stir until smooth. Serve waffles with warm compote and yogurt topping.