Not the best of barometers as the Office 2007 compatibility pack was released for Office 2003 that allows them [clients] to view the newer formats , I know of a few places this is used.
Office generates about the same revenue as Windows (would you believe it or not), and I don't see people intentionally bashing Office 2007 like Vista . I think most enterprises will retain their old Office 2003 machines, but on new machines you can have XP,
but definitely take Office 2007. There is a tonne of business value there, unlike Vista.
While I understand while MS might want to guard these secrets, but it sure would be helpful in convincing devs to help push forward with software targeting current-version software.