Doug Mahugh had a post a couple days ago where he provides some basic code that will generate a WordprocessingML document: http://blogs.msdn.com/dmahugh/archive/2006/06/27/649007.aspx

Some folks have been asking about examples of how to create a basic document with the required relationships, content types, and parts. Doug had actually blogged on Monday that he would put up examples for all three document types, and this is the first of those examples.

Doug is very active on the OpenXMLDeveloper.org site, and it's great to see him pulling some examples together like this. Thanks Doug!

-Brian