Interesting report on podcasts and consumers

This archived audio/slide presentation with PDF is very interesting, it gives some numbers on usage of downloadable media by consumers. It's by Edison Research.
Just skimming it, I was struck that 57 % of Americans haven't heard of podcasting. That's based off a phone survey done this January of 1858 random Americans. And 22 percent of people have listened to at least one podcast in their lives. The presenter, Edison's Vice President of Strategy and Marketing, Tom Webster, said this number was an indication that podcasting has hit the mainstream. To me one out of five people is not mainstream, but maybe I need a lesson in relativity.
Anyway, the slides are very interesting and I'll try to take an hour, maybe at lunch breaks at my desk, to listen in.