Here's a blog entry I just came across where the user is building an XSLT that will transform their data into WordprocessingML (http://dbdesc.com/blog/?p=10). It's followed up by another post that was made today (http://dbdesc.com/blog/?p=11). This is a cool example of how you can start playing around with the document generation capabilities that come with XML file formats. This is really just the start or course, which is why it's fun to see.
We're seeing a lot of people doing similar things. Like I said earlier, we currently have a huge community of developers building solutions on top of Office (about 1 million), and 1/3 of those people are using the XML functionality in Office 2003. That's 330,000 people developing solutions using Office XML. I can't wait until we get Office 12 out there, and people can rely on full fidelity XML formats in all three applications (Word, Excel, and PowerPoint).