The change is expected to be integrated in Firefox 7, which is due for release at the end of September. While it seems to be only a cosmetic change, the purpose is to highlight the current browser location in a much more meaningful way and drop the protocol prefix, which has been confusing especially to users that are new or not familiar with the Internet. Firefox also greys out the "www" or subdomain of a URL, as well as the resource ID and deletes any trailing single slashes in a web address.
To maintain a reasonable level of security while browsing, Firefox 7 still displays the https:// prefix, to inform the user when the browser is showing a "secure" webpage. Firefox will also include the prefix when users copy and paste URLs from the location bar.
Mozilla said that it is following both Chrome and Opera with the elimination of the prefix. Chrome dropped the prefix with the release of developer versions of Chrome 5 back in April of 2010.