What makes seasoned cast iron non-stick? I get how Teflon works, but am curious how the act of seasoning cast iron makes it non-stick. Does this also work for other metals besides cast iron?
 A: Oil polymerises when it reaches it smoking point, forming a hard coating with non-stick properties (not as non-stick as Teflon). It works on any metal, and is also recommended for aluminium roasting pans. One manufacturer has a slogan "the blacker it gets, the better it cooks"
A: The surface structure of that type of cast iron is somewhat porous, which makes it take up oil readily, and then polymerize it with heat. With the passage of time, all the surface pores get plugged with polymerized (solid) oil, and the food cooks in contact with that layer- and not with the iron itself. 
This naturally-forming nonstick layer requires care to maintain. Each time you fry something with that pan, you have to start with pouring in a nice layer of fresh oil (always a good idea!), and you must take care to never wash the pan in soap nor scrub it with abrasive. 
And... you should never cook acidic foods (like tomato sauces) in it, because the acid will find pinholes in the coating and promptly attack the iron beneath it. 
