See also WhereAmI for another take on this problem.

ThomasHeller posted this tip to the mailing list:

`main_is_frozen()` returns `True` when running the exe, and `False` when
running from a script.

`get_main_dir()` returns the directory name of the script or the directory
name of the exe - this is also sometimes useful.

{{{
#!python

import imp, os, sys

def main_is_frozen():
   return (hasattr(sys, "frozen") or # new py2exe
           hasattr(sys, "importers") # old py2exe
           or imp.is_frozen("__main__")) # tools/freeze

def get_main_dir():
   if main_is_frozen():
       return os.path.dirname(sys.executable)
   return os.path.dirname(sys.argv[0])
}}}