NewsCom

News.Com: "Microsoft has yet to disclose the proprietary dialect, or underlying schema, of the XML used in Office 11."

All Office products will output to an XML file, which would be viewable via any browser, but editable only from within the originating office application--or by a very, very skilled XML programmer

So its going to be more complicated than <xml><worddoc>blah blah</worddoc> then - wow, why am I not surprised.