«Podcasting is about as long tail as it gets. Although there are a few highly-rated podcasts with more than 100,000 listeners/viewers, most podcasts have far smaller audiences, highly-focused on niche interests.
According to long-tail theory, these targeted audiences should be especially valuable to advertisers and marketers. Although the audiences are small, each listener or viewer is very interested in the subject, and the audiences should therefore carry commensurately higher ad pricing. (...) “Podcasting is, by its nature, a niche medium, and this is not likely to change," said Paul Verna, senior analyst at eMarketer. "But podcasting delivers a level of end-user engagement that is rare in today’s multi-format world.”» (Remember Podcasting? Listeners Do. eMarketeer, APRIL 24, 2008