A team of Russian hackers has found a way to decipher a Yahoo CAPTCHA, thought to be one of the most difficult, with 35% accuracy. The Russian group's notice, posted by one "John Wane," is dated January 16. This site hosts a rapidshare link to what looks to be demonstration software for Windows, and quotes the Russian researchers: "It's not necessary to achieve high degree of accuracy when designing automated recognition software. The accuracy of 15% is enough when attacker is able to run 100,000 tries per day, taking into the consideration the price of not automated recognition " one cent per one CAPTCHA.

http://internetcommunications.tmcnet.com/topics/broadband-mobile/articles/18772-yahoos-captcha-brokenis-spam-tsunami-the-offing.htm
http://network-security-research.blogspot.com/
http://www.0x000000.com/?i=502
http://rapidshare.com/files/84243632/YahooCAPTCHARecognition.rar.html