I read this note on Dave Winer's blog:
Fran: "I talked to over one hundred occupational therapists, and only 3 had ever heard of podcasting."
My first thought: What kind of condition could Fran have that the first 99 occupational therapists couldn't help her? Second thought: Imagine the paperwork in getting an insurance company to pay for all those sessions... A second or two goes by, and I realize she (or he) must have spoken to a group.
I will add, in backing up Fran's point, that very people I'm talking to in the worlds of datamining, math and operations research are talking to me about blogs or podcasts. For enormous swaths of computer-literate humanity, blogs and podcasts are like electrical storms over distant mountains. You look at them and think, hmmm, at some point I may have to pay attention.