I just found this while browsing the sessions page for MIX08. Yeah, I'll definitely be attending this presentation. This is information I'd love to see presented to the PDXUX.Net group. Read more about it on the MIX blog.
The Story of the Ribbon
Speaker(s): Jensen Harris
Audience(s): Creative
Session Type: UX Track
Farewell, menus and toolbars! Come hear the behind-the-scenes story of how the 2007 Office Ribbon user interface was imagined, designed, and validated. See never-before-shown early prototypes, hear about mistakes we learned from during the design process, and find out the principles of user experience design we used each step of the way in creating the first totally new user interface for Office.