If you call reload() with a module that was imported from 
a zip, it fails with a "no such module" error.  Although 
zips are typically read-only, it is possible that a zip could 
be modified during a run, and a reload be necessary.  If 
this is considered unnecessary, then I think a more 
informative "can't reload from zip" error would be better 
than a 'no such module" one.

"""
>set PYTHONPATH=path/to/spambayes.zip
>python

>>> from spambayes import Options
>>> Options
<module 'spambayes.Options' 
from 'c:\spambayes\windows\py2exe\dist\lib\spambayes
.zip\spambayes\Options.pyc'>
>>> reload(Options)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ImportError: No module named Options
"""

This is with Python 2.3.2 and WinXP.