I read this article on Salon.com about how using hideous typeface in your presentations actually helps people retain the information you're sharing. Since this was a Salon.com article, it was more about typography than learner outcomes, but the article is based on an education study [pdf] that definitely messes with some of my assumptions.
If you're like me, you dream of super slick lesson plans that allow information to flow effortlessly through your students' brains. This study suggests that when we make it easy for students to take in information, we also make it easy for them to forget the information--in 15 minutes or 15 days or after they take the test. If we make it a little harder--by, say, writing the information in a jazzy font--we engage their brains better and help the info stick.
I still think the typeface thing seems kind of gimmicky. Although the article points out that it's cheap and easy to implement! And I'd like to tell the guy in the Salon.com article who worries that the Kindle makes it "too easy to read" that I can give him more serious things to worry about if he's interested. But I like the idea of "desireable difficulties." In what ways do I want my students to struggle, grapple, and wrestle with information?