A little off topic, but quite interesting: If you decompress a 2007 document (e.g. docx) using a standard decompression tool like IZARC or similar it will leave you with a full XML document structure. This leads me to conclude that all the 2007 formats are just zipped XML files making Office 2007 docs actually pretty open and readable in lots of ways.
They are... The 'problem' is that a lot of the actual markup tags are extremely poorly documented, and things like 'LikeWord95' and such have no documentation at all, making it essentially impossible for anyone but Microsoft to create a 100% compatible loader/converter.
The XML makes it very easy to extract the actual human readable text strings, but decypering the layout still requires voodoo.