****UPDATED 12 JUNE 2009****
The Ecma TC45 technical committee has shared some presentations with us that cover the basics of PresentationML. PresentationML is an area that very few people have delved into yet, as opposed to WordprocessingML and SpreadsheetML, so if you're eager to get started on working with PresentationML you'll want to check these out.
This information is coming direct to us from the technical committee responsible for developing the Open XML standard.
A number of resources have been developed from the Ecma presentations, and can be found here (modeule 08: PresentationML). Included are:
Presentation - this has an overview of PresentationML, along with lots of examples, code snippets and general useful information
Samples and Hands On Labs - step by step guide to using PresentationML with the finished examples also supplied so you can check your outcome against the worked outcome.
If you have comments or questions, post them in the Forums section of this site, and keep an eye on Brian Jones's blog for more information.