Code licensing practices

Should I put the license in the header of every source file? or just in the module that handles the imports/includes of all of them?

e.g.
mymodule - Contains license in the header
-imports: myothermodule
-includes: mytypes.bmx, myfuncs.bmx, etc (do these have to contain the license as well? or does the including of code inherit the licensing?)
myothermodule - Contains license in the header
includes: etc..

I'm going to be using the MIT license for my duct modules (Google code :o).

I do. Can't really miss it then ;-)

As for Includes... I've never used one... but since it'll just be a comment, I don't suppose there'd be any harm having them in there also.

I usually don't bother with licenses in the examples source.

Hehe, good point.

I figured that much :)