Coincidentally, today I received a link to an article [large pdf file] discussing how PowerPoint contributed to (among other things) underestimating the risk of the foam impact on the wing of the space shuttle Columbia on its ill-fated mission. The article can be summarized as "Power Point makes form and presentation more important than content and logic, dulls the audience's critical thinking with its familiar formula, and hides BS behind pretty graphics: thus leading to invalid conclusions". If the WT doesn't let speakers user Power Point, I think they're missing the point!
GLT
(sorry about that bad pun)