Preheat oven to 400 degrees. Lightly grease twelve 2-1/2 inch muffin cups. Combine flour, baking powder, salt, and cinnamon on sheet of waxed paper.
Beat bananas in large bowl with electric mixer until mashed. Add eggs, brown sugar, butter, and vanilla, beating until blended. Stir in combined dry ingredients with a wooden spoon until almost blended. Stir in blueberries just until combined. Spoon into prepared muffin cups, dividing batter equally.
Prepare Topping: Combine sugar and lemon rind in small dish. Sprinkle evenly over muffins.
Bake in preheated oven for 20 to 22 minutes or until golden. Remove muffins from pan to wire rack. Serve hot.
Makes 12 muffins.