web page: "gpl" (note that without a version number, this maybe could be interpreted as either gpl v1, or any gpl version, or the latest gpl version)
README link: links to gpl v3 (this is an issue of the FSF web page, the URL contained gpl v2 before v3 was released, maybe it'll contain gpl v4 some day?)
module docstrings: gpl v3 (note that this must be interpreted as "gpl v3 only")
longer comment in code below docstring: "gpl v2 or later" (this is copied from GPL v2)
setup.py: License :: OSI Approved :: BSD License
COPYING: GPL v2
Maybe talk to me about this. I recently cleaned up licensing in MoinMoin (which was only "cosmetically" inconsistent) and wrote some tool to do some automatic source code editing to get the stuff into a 100% consistent state.
IANAL, but I can maybe help with choosing a license, too (at least I know some of the issues of different GPL versions).