Channel 9 has posted a great video interview and demo of how OpenXML easily allows interoperability with back-end systems on the LAMP stack.  This demo was created by developers at Sonata Software who specialize in IT development and global off-shoring.  The company is based in Bangalore but has clients throughout the world.

Also though the video is not of the highest quality, the functionality exposed through the OpenXML stack is impressive.  To note is the back-end ability to capture document revisions and manipulate that information so that it can be consumed in a custom environment using Javascript.  The presentation shows that OpenXML is not as complicated as the folks in the ODF camp would like you to believe, in fact, the developers only implement XML for the functionality they want to capture in the application while leaving alone all the other bits found in a typical Office file. 

To be completely fair, this demo could probably be implemented using ODF as well but the main reason no one in there right minds would want to use ODF is that it doesn't support all the advanced functionality of the Office 2007 system.  With OpenXML, developers can implement the entire specification if they wanted to and be compatible, which is not the same with ODF.