Seems similar to the discontinued Google Sesame. http://www.zdnet.com/open-sesame-googles-no-password-log-in-...

It would be interesting to know why Google didn't pursue it. Maybe a 20% project? https://plus.google.com/101935995649723391317/posts/P94xEz9D...

Another similar system http://corp.galois.com/blog/2011/1/5/quick-authentication-us...