Eric White on the team has just released his PowerTools PowerShell cmdlets for OpenXML onto Codeplex.
The PowerTools for Open XML is sample source code and guidance for developers showing how to build PowerShell cmdlets that can create and modify Open XML documents. Also included are a number of examples of PowerShell scripts that use the cmdlets.
For me, one of the cool uses is the ability to run the cmdlets from the command line remove all the comments from a word document or powerpoint file. Imagine there are also many other possibilities, such as combining this with Sharepoint workflows to do this same thing automatically for any external presentations that hit a certain folder...
You can download the samples and documentation at the following location ( http://www.codeplex.com/PowerTools)