Good question panic button. I have often wondered that. A guess would be that one side is coated in order to damage the lungs of people free basing but I'm not sure if that's the case or not. Might just be how it solidifies after being molten? I really don't know!
a very old and nasty cookery teacher once told me that the matt side goes on the outside as the shinny side reflects the heat back on to the item being cooked so aiding the cooking process and not away from the food, but i really did not like her and would love someone to tell me different and proove her wrong lol
From what I've read the difference is due to the manufacturing process
When aluminum foil is manufactured, it's so delicate that the presses that flatten it will tear it unless two sheets are pressed together. Thus, the shiny side is the side that presses against another sheet. Neither side conducts heat any better or worse than the other.
there was a scare many years ago that the aluminum that got into food from saucepans and foil may of contributed to altzhimers (sp) thats what i would imagine tonyted is refering to