In my opinion, the new Office 2007 user interface is one of the most innovative things to come out of Redmond in years. It's nothing less than the death of the main menu as a keystone GUI metaphor. This is a big deal. Historically, where Office goes, everyone else follows. It's already starting to trickle down: IE7 does not show its main menu by default, and neither does Vista. You have to press Alt to expose the menu. The main menu has been demoted to a sort of configuration panel for advanced users; for everyone else, there's the Ribbon and toolbar buttons.