The note at the end of the pkgutil.walk_packages() (and iter_modules()) documentation can be improved somewhat:

http://docs.python.org/dev/library/pkgutil.html#pkgutil.walk_packages

For example, "importers" aren't referenced earlier in the documentation of the function, so it's not immediately clear what they are referring to.  I also think that enough information should be given so that one can run the examples given and have them work.  They currently don't.

I can put together proposed wording.  See the issue 14982 discussion for background.