Google acquires ReCAPTCHA
Google has acquired a Carnegie Mellon University spinoff that seeks to cut down on spam and fraud at websites while digitizing books.
ReCAPTCHA offers simple word puzzles that users must solve when registering at a website or completing an online purchase. Computers can't decipher the twisted letters and numbers, ensuring that real people and not automated programs are using the site.
http://www.cbc.ca/technology/story/2009/09/17/tech-google-recaptcha-017.html