The Cognitive Style of PowerPoint

I just finished presenting an 8 hour tutorial and two presentations using 
PowerPoint at a conference where they strongly prefer that we write our 
presentations in XML. When I went through my email, I found this:

http://www.nytimes.com/2003/12/14/magazine/14POWER.html

What is the "cognitive style" of writing documents in XML vs. PowerPoint, 
Word, or FrameMaker? Do the tools we use to write affect the way we think?

Jonathan