It looks like Microsoft Office has gone the way of Open Office for its next change of file formats. The new file ext will be .DOCX, .XLSX, .PPTX and basically they will be .zip files (so they should be able to be opened with something like winzip), and will contain a bunch of XML files that you can look at. Microfsoft will also make the shema's and everything else fully assessable - believing that its the software which adds the value - not the file(format).