Brian Jones has a blog post entitled Corel to support Microsoft Office Open XML Formats which begins

Corel has stated that they will support the new XML formats in Wordperfect once we release Office '12'. We've already seen other applications like OpenOffice and Apple's TextEdit support the XML formats that we built in Office 2003. Now as we start providing the documentation around the new formats and move through Ecma we'll see more and more people come on board and support these new formats. Here is a quote from Jason Larock of Corel talking about the formats they are looking to support in coming versions (http://labs.pcw.co.uk/2006/01/new_wordperfect_1.html):

Larock said no product could match Wordperfect's support for a wide variety of formats and Corel would include OpenXML when Office 12 is released. "We work with Microsoft now and we will continue to work with Microsoft, which owns 90 percent of the market. We would basically cut ouirselves off if you didn't support the format."

But he admitted that X3 does not support the Open Document Format (ODF), which is being proposed as a rival standard, "because no customer that we are currently dealing with as asked us to do so."

X3 does however allow the import and export of portable document format (pdf) files, something Microsoft has promised for Office 12.

I mention this article because I wanted to again stress that even our competitors will now have clear documentation that allows them to read and write our formats. That isn't really as big of a deal though as the fact that any solution provider can do this. It means that the documents can now be easily accessed 100 years from now, and start to play a more meaningful role in business processes.

Again I want to extend my kudos to Brian and the rest of the folks on the Office team who have been instrumental in the transition of the Microsoft Office file formats from proprietary binary formats to open XML formats.