how embarassing, i make a point of asking for comments and critique on my previous post but comments didn't actually work unless you're logged in. I only noticed because someone emailed me.
It was the admin-ssl plugin. de-activated now, so comments are working again.
A few people tried to add comments according to the log – if you feel like making them again, go right ahead.
This is why it's a good thing you have your email address discoverable on the blog's About page ;)