President Obama's appearance on "WTF with Marc Maron" was a milestone for podcasts. 36 hours after being posted, the podcast had been downloaded more than 900,000 times according to Libsyn which distributes the program. 735,000 downloads in 24 hours. The show typically does about 200,000 in 24 hours.
The notion that the President would sit down in a garage with a podcast host versus the more mainstream press and typical network outlets is remarkable, and of course the coverage highlighting the podcast is irreplaceable.