I think maybe the world has moved on from Pyblosxom and, as my logs can attest, spammers seem to have moved on past Recaptcha (even if it is manual).
However, maybe there are some other holdouts like myself who will find this plugin useful. In reality, this will do nothing for stopping spam — for that I am currently having good luck with Akismet. However, I like that in displaying the captcha it costs the spammers presumably something to crack it so they can even attempt to submit the comment.