I had a captcha plugin that was failing. Since I myself hate captcha’s, I’ve removed it for now and adjusted the comment settings to require moderation the first time you comment. Moderation + akismet should take care of most of the spam (hopefully). You can also still sign in using OpenId if you prefer, although the openid login on wordpress remains quite underwhelming (compared to what should be possible by now).
Anyway, happy commenting and thanks @eelkefolmer for pointing out my site was broken.