In a large bowl stir together the cereal and buttermilk; let stand for 10 minutes, until soft. Preheat the oven to 375F.
Stir the sugar, oil and egg into the bran mixture. Add the flour, baking powder, baking soda and salt and stir until almost combined; add the peach and stir just until blended.
Divide the batter among 12 muffin cups that have been lined with paper liners or sprayed with nonstick spray. Bake for 25 minutes, until golden and springy to the touch.