Microsoft spends four years on Office 2007. Yes, four years is such a long time. However, what makes you WoW? Just Ribbon UI and XML file format are two important things I notice. Even though the new file format is not well treated by users, Ribbon UI has received a lot of reviews.
It is apparent that somebody loves it while others hate it. However, now Ribbon enters a new field Microsoft never imagines. The field is development tools.
If you know NDepend, a wonderful code analysis tool for .NET, you may see the coming version with Ribbon UI.
And if you try InstallAware, you see Ribbon too. It is surprising that InstallAware does not publish even a screen shot of the user interface on its web site. I notice this feature only after installing the tool.
Yesterday, when I read about MonoDevelop, I found that the guys might do a Ribbon UI in future versions too. Now GTK# Ribbon Library is nearly complete, so it is quite possible to see a Ribbon driven MD.
Will one day we see Delphi or Visual Studio with Ribbon? Wait and see.