You probably haven't noticed, but I've made some comment system changes in the last few days that are really effective at blocking spam. I got the ideas from this article. It looks like one of the changes had a bug that made comments unusable for a couple of days, but it's fixed now.
For the curious, the comments form now contains a hidden email field. Any human users won't see it, and thus won't fill out that field. But a spambot sees the field marked as an email field and fills in an email address, causing the comment system to instantly recognize the comment is spam. Also, there's now a timestamp so spambots can't resubmit the same forms with different information each time.
None of these changes should affect the way that regular users leave comments on this site, but there should be less or no spam. Let me know if you run into any issues via the contact link at the top of the page.