Google has acquired reCAPTCHA, which provides CAPTCHA technology for more than 100,000 Web sites. reCAPTCHA is a spinoff of Carnegie Mellon University's computer science department.

A CAPTCHA is a bit of text that Web sites use to verify that it's indeed a human being on the other end of the line -- not a spam robot or computer. (Though they're not 100% secure, CAPTCHAs tend to block out most spam. We use reCAPTCHA, for example, on our anonymous tips form.)

The twist in the deal that could help Google is that many of reCAPTCHA's words come from scanned newspapers and old books. By having humans type the scanned words into reCAPTCHA, they get help reading the scanned text. This could be helpful for Google's book scanning project.

Creator Luis von Ahn will remain on the CMU computer science faculty, but will also work at Google's Pittsburgh office.