Update
As of September 12, 2005, the following documentation has been released for the iWork apps’ XML specifications. Very nice! Thanks, Apple!
http://developer.apple.com/documentation/General/AppleApplications/Conceptual/iWork2-0_XML/index.html
This precludes us from having to use the “Standard Warning” (about using undocumented General/APIs / Specifications). This page can now be re-factored as a how-to / example code page. Yay!
And it looks like the file format may suck: http://www.tbray.org/ongoing/When/200x/2005/09/18/Apple-XML
Is there any example code out there showing how to open and display contents of these files, especially Keynote?