Firefox 22 Will Block Third-Party Cookies
 

Firefox is about to make a change in the way the browser handles third party cookies. With the release of Firefox 22, which is several versions out, all third party cookies will be blocked from installing on the user's browser. This will effectively stop advertisers from tracking the user's movements across websites. With the patch, Firefox would allow all cookies from sites that a user actively visits, but would block cookies from third-party sites if a user has not visited that cookie's origin site.

http://www.hardocp.com/news/2013/02/...party_cookies/