It looks more like IE7 or Chrome than it does any version of Office.
- hid the menubar.
- condensed common menu items into Page and Tools drop-downs, to apply to the current page and whole app, respectively.
- merged the search and address bars (which imo should never have been separate--I always hide the search bar).
- merged some other buttons (stop/reload etc.).
- plan to simplify the 4 different ways to access bookmarks.
Full description of mockup here: https://wiki.mozilla.org/Firefox/Sprints/Windows_Theme_Revamp/Direction_and_Feedback
Other than a brief mention of possibly adding ribbon styling, none of the above looks much like Office ribbons to me.