Jill A. S., 10/26/12
I am a professional chef, and I can tell you from experience (and it was on Mythbusters for that matter) that it makes absolutely no difference which way the aluminum foil faces (opposite of what I learned in Boy Scouts).
Shiny side in / Matte side in has no effect, the difference in the surface of aluminum foil is a result of the manufacturing process and has no bearing on heat retention or reflection.
Thanks for the good write-up!
Matt, 11/15/12
James, 11/23/12