Mozilla engineers have tweaked the current nightly build of Firefox to not show favicons in the address bar. However, the favicons will be there on the tab bar. Starting from Firefox 14, the address bar (URL bar) of Firefox will show a globe icon for all ordinary websites and padlock icon for all websites using SSL encryption.
Mozilla’s Jared Wein explains the reason for this minor but important UI change, “While the favicon can represent a piece of a site’s identity, there are some sites that set their favicon to a padlock. This behavior can trick users in to thinking that a site is using a secure connection when on an unsecured connection.”
Moreover, the websites using SSL certificates with extended validation will have a green padlock icon, while the sites using SSL without extended validation will have gray padlock icon (as in the above screenshot, case #3). This change will certainly increase security for the end-users specially when a site is trying to mislead them. Firefox recently removed http:// and single trailing slashes from the address bar.
Just to mention here, Chrome and Opera already have this feature. Opera has implemented it in a very impressive manner.