That flashy statistic is courtesy of the My Podcast Reviews service, by Daniel J. Lewis.
Note also that the number of podcast shows has broken 900,000, approaching a benchmark of one-million. Those numbers represent “valid” podcasts, meaning shows which offer downloadable episodes, even if they are old and the show is no longer in production.
My Podcast Reviews notes that over 47,000 shows have been added in the last 30 days.