__all__ as a determiner of a module's api needs to be 
more fully documented. The only references I found were 
at http://www.python.org/doc/current/ref/import.html and 
http://www.python.org/doc/essays/packages.html. I also 
think the various uses of __all__ might be worthy of a 
small PEP, since I can't find any supporting 
documentation for the use of __all__ as anything more 
than controlling import *, which to me is not exactly the 
same thing as defining the public api for a module. It 
could be, and if it is meant to be then tools, such as 
IDLE, Boa, PythonWin and PyCrust should take __all__ 
into account when displaying autocompletion lists for 
modules.