Jensen Harris from the Office 2007 design team gave a very rare presentation at Microsoft"s MIX08 event yesterday about not what the Office 2007 Fluent (Ribbon) interface is about, but instead how it came to be and what other concepts they tried.
He admitted himself it was the first time ever in a public venue where they"ve shown these never-before-seen prototypes of what would become Office 2007. It was great insight into the development process of Office which frankly may not have been very interesting except the last release. Having said that, it was still a very small selection of material out of the 50-60GB worth of prototypes Jensen claims have been archived.