Thanks, all! Now it seems obvious, of course.

Yes, it is just like "flouring a pan". Same principle. It adds a little flavor, a little texture, and does not add flour or gluten to the dough.

that is exactly what it means. you'll see it a lot in pizza recipes. just throw a handful of cornmeal on the baking sheet (or pizza stone if you have one) before you put the pizza on it. it is so the pizza doesn't stick to the pan.

I really want to make this recipe: http://threemanycooks.com/recipes/nibbles-and-apps/smokey-bacon-caramelized-onion-pizza/

But what is a "cornmeal-coated baking sheet"? Does that mean I should spread cornmeal on a baking sheet (seems odd), or is this something I've just never heard of?