Some things I saw in the Python 2.2(+.1c1) release notes ... need
to check if these apply to us also:

 - The "pseudo-sequences" returned by os.stat(), os.fstat(),
   time.localtime() can now be pickled.

 - pickle.py, cPickle:  allow pickling instances of new-style
   classes with a custom metaclass.

 - In pickle and cPickle, instead of masking errors in load() by
   transforming them into SystemError, we let the original
   exception propagate out.  Also, implement support for
   __safe_for_unpickling__ in pickle, as it already was supported
   in cPickle.