I thought about mentioning this, but Menus still had a tendency to dead-end into modal dialogs more often than not. A Ribbon command could still end up in a modal, but often times the Ribbon design allowed more functionality to be present in a non-modal way.

I worked for Lotus/IBM when Word Pro was being developed, and they came up with the concept of a non-modal floating property bar (they called it the "Info Bar") that pretty much eliminated modals entirely. While I don't recall whether or not it was very keyboard friendly (I was still a mouse user at the time), it definitely showed me that there was a better way than "modal dialogs everywhere".

When I moved on from IBM and had to use Office, I remember how grating it was every time I ended up in a modal dialog, so this was one more reason I was excited to see the Ribbon come along (more than a decade after Word Pro's Info Bar).

I've never looked to see, but it wouldn't surprise me if some of the MS developers for Office 2007 came from Lotus/IBM, since it was a few years earlier that IBM had really given up the Office Suite fight for good.