Some projects use module variables like __license__, as in:
__author__ = "Software Authors Name"
__copyright__ = "Copyright (C) 2004 Author Name"
__license__ = "Public Domain"
__version__ = "1.0"
Seems like a pretty clean solution to me (unless you overdo it and dump epic texts into these variables), but only __version__ seems to be in widespread use, as it is mentioned in PEP 8.