“If [the spammers] are really able to write a programme to read distorted text, great – they have solved an AI problem,” says von Ahn. The criminal underworld has created a kind of X prize for OCR.

Reading the ubiquitous CAPTHCAs (those smeared words that are often impossible for even humans to read) is a big incentive to design new optical character recognition algorithms.  I don’t understand the article’s connection to “Turing tests” but the economics are interesting.  Spam is an inefficient way to provide incentives for research, it would be better to just use cash.  But since they are going to try to spam us anyway (the cash just adds to the incentive), we might as well keep the cash and reward them with spam.