In the past few days (I can't remember when this started, I think around 2011-10-20 give or take a couple of days), I've had far more captchas than usual. I'm getting more than one a day, when until then I'd never get a captcha for posting an answer, only for unusual behavior (like make multiple edits or many comments or cast many votes in quick succession). In each case, I was just posting an answer (or in one case a question), I hadn't done anything unusual or strange.
Today I've had four captcha requests: two on Unix, one on Travel, and one on — I'm not 100% sure now (it was a couple of hours ago), but I think it was French. How many times do I need to prove that I'm not a robot‽