I use this plugin as well as Akismet. Akismet has detected 779 spam comments on my blog in November alone. That's 779 spam comments that have defeated the SI Captcha plugin... (none of them came from registered users) That makes me think that there's either an implementation weakness or spammers are able to OCR the image? My blog is not high traffic at all, and I don't think they'd muster up a relay attack for it. Any suggestions?