Burning Door, Feedburner's official blog, recently posted a 'state of the podcastsphere'-like post containing some interesting (to me, anyhow) stats.
I'll spare you all the gobbledy-gook and just highlight the things that kind of surprised me. If you want the full onslaught of numbers,.
43% of podcast listeners don't use iTunes. That's higher than I thought.
The two biggest jumps in listenership were last June and around Christmas. June is when iTunes 4.9 (with podcast support) was launched and Christmas...well...lots of shiny new MP3 players opened at that time of year
Resyndication is driving a lot of listenership. Resyndication means listeners subscribing from sites other than the podcaster's such as Podcast Alley or Podcast Pickle.
If you're interested in hearing the Feedburner guys speak (although not specifically about podcasting), Eric Olson and Traci Halipern on are episode #10 of my JaK Attack! podcast.