Preheat oven to 350 degrees F (175 degrees C). Grease and flour a muffin pan, or use paper liners.
In a large bowl, combine sugar, oil and eggs. Beat until smooth. Blend in banana and vanilla. Mix together flour, baking powder, baking soda, salt and cinnamon, then stir into egg mixture until just moistened. Mix in the prunes. Spoon into muffin cups.
Bake in the preheated oven for 20 to 25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.