Looks like either they've broken the CAPTCHA methods used by das Blog, or people are hand-posting comment spam.
I think that email spam may be using keywords derived from my blog as part of their randomly generated subject lines. That's a clever way to get around any Bayesian filter.
I assume that when not randomly generated, if you see the same or very similar spam subject lines, they're effective at producing click-throughs. If so, that's depressing.