Updated version with bug fixes and new cmdlets. In particular, Merge-OpenXmlDocument allows you to create new documents from all or part of multiple source documents. Check the README for more details.
Update: March 19, 2009 - updated DocProc.zip - fixed an bug where it didn't resolve issues with images in headers and footer. The download Open_XML_PowerTools.zip already contains this fix.
Update: March 27, 2009 - DocProc.zip - now contains the code to handle charts from the PowerTools.