Podcasting advertising to pass $400 million within five years

eMarketer estimates that the total US podcast audience reached 18.5 million in 2007.

Furthermore, predicts eMarketer, that audience will increase by 251% to 65 million in 2012. And of those listeners, 25 million will be “active” users who tune in at least once a week.

What does this mean for advertising?

How does $435 million by 2012 sound?

Interestingly, one of the reasons eMarketer gives for this growth is, of course, terrestrial radio’s use and promotion of podcasting.

Who’s sponsoring your podcasts?