Brian Jones has announced the posting of the Microsoft Office Binary Format specs on this blog.

Along with these formats we have also provided a few additional format specs:

• Windows Compound Binary File Format Specification PDF | XPS
• Windows Metafile Format (.wmf) Specification PDF | XPS
• Ink Serialized Format (ISF) Specification PDF | XPS

And the "Office Binary (doc, xls, ppt) Translator to Open XML" project is now live on sourceforge: http://b2xtranslator.sourceforge.net/

Happy Coding.