Bit of useless trivia for you: Why is one side of aluminum foil shiny while the other is dull?

From wikipedia:

For thicknesses below 0.025 mm (0.001 in), two layers are usually put together for the final pass which produces foil with one bright side and one matte side. The two sides in contact with each other are matte and the exterior sides become bright. This done to reduce tearing, increase production rates and to help control thickness.

First heard this on an episode of Good Eats. Makes sense.