The interesting thing about these human-based attempts to defeat individual CAPTCHA-"protected" services is that if they are actually reCAPTCHA or variants, they perform a strong socially useful function!

This is because reCAPTCHA solving is linked to the digitization of paper documents.

There was recently a TEDTalk by the inventor of the CAPTCHA about this topic. It is very informative and entertaining. I highly recommend it: http://www.youtube.com/watch?v=-Ht4qiDRZE8