OpenOffice  1.1 beta now supports DocBook  Import/Export as indicated by the feature list .
1dok.org works on an open standard for free and unimpeded exchange of electronic documents via internet.
In case you haven’t already heard: The OASIS standardization organization founded a TC to create an open, XML-based file format specification for office applications.
“This year’s upcoming debut of Microsoft Office 11 will mark the start of a long process of education and adaptation. […] So here we’ll explore how existing Office documents can benefit from the new features, how developers will prepare XML-aware Office templates, and how users will apply them to create and analyze XML data.”