Tim Lyth wrote:

The "greylist" filter included with pythonfilter is actually newer than the one on Georg's site. I incorporated most of his improvements, and merged his secondary scripts into the filter.

That said, the most significant of his improvements, the whitelists, probably aren't necessary anymore, since pythonfilter has significantly better whitelisting facilities now than it did when Georg wrote his version. At some point I'll probably remove the greylist filter's internal whitelists in favor of the general whitelists.