The results from this script

  import os, sys
  print('Python %s' % sys.version.split()[0])
  print('env[LANG]: %s' % os.environ.get('LANG', '<not set>'))
  print('default encoding: %s' % sys.getdefaultencoding())
  print('filesystem encoding: %s' % sys.getfilesystemencoding())

are with Python 3.0:

Python 3.0rc3
env[LANG]: <not set>
default encoding: utf-8
filesystem encoding: utf-8

but for Python 2.3 thru 2.6:

Python 2.6
env[LANG]: <not set>
default encoding: ascii
filesystem encoding: utf-8

All with Python built from source on MacOS X 10.4.11 (Intel).