I recently re-discovered Sam Ruby's automatic trackback scipt for pyblosxom entries and made some tweaks for my own purposes:

1. Permits paths/categories, the original did not make use of them.
2. Grabs configuration information from the pyblosxom config.py file.
3. Works with my htmlentry plugin.

Unfortunately, I noted — too late — that an autoping.py also comes with pyblosxom, which includes some of Wari's tweaks for caching, so that's three variants! Oh well, perhaps someone will have some time to re-factor the best of each.