Reflective wrote:It would appear that Mozilla is going the Safari route to block third party cookies by default. It's also been suggested that users clear all cookies before installing that version which is a bit controversial.
More on the subject here: The New Firefox Cookie Policy
The post isn't entirely accurate, only 3rd-party cookies (coming from websites other than the website which you are currently visiting, frequently tracking sites, but also content sites for images, etc.) from websites which you haven't been actively visiting before are blocked.
For example, if Facebook wants to set a cookie for a "Like" button in another web page, it initially wouldn't be allowed to do so. But, if you go to the primary Facebook website to view some stuff, thus acquiring some permitted cookies from that visit, subsequent return visits to the other site would now allow the "Like" button to use the 3rd-party cookies as there has been a permitted "visit" of that site before. From the user-tracking point of view this leaves some loopholes, but it's better than the previous default which just blindly allowed the 3rd-party cookies, thus supporting tracking.
This breaks the Privacy & Security > Cookies preference pane on trunk, I've filed bug 845353 on that.