Preheat oven to 400�.
Generously grease muffin pans, or use paper liners.
In a large bowl mix flour, sugar, baking powder & baking soda. Cut in butter using a pastry blender or a fork, until mixture resembles fine crumbs.
In a small bowl, stir yogurt until creamy. Blend in eggs & vanilla extract. Pour all at once into flour mixture & stir until flour mixture moistened. Do not overstir. Gently fold in blueberries.
Fill prepared muffin cups 2/3 full. If desired, sprinkle the tops of the muffins with a bit of additional sugar. Bake for 15-20 minutes, or until golden brown.
Remove from pans immediately. Serve warm.