Two new important resources for anybody doing Office 2007 client programmability:

Doug points to two new podcasts on the Open XML File Format and the options for developers.

PART 1 - http://channel9.msdn.com/Showpost.aspx?postid=246549

PART 2 - http://channel9.msdn.com/ShowPost.aspx?PostID=247408

Jensen has the link to the final schema for RibbonX, the XML file you have to create if you want to extend the Office 2007 user experience.