MediaWeek reports that podcasting is poised for a major growth spurt in ad dollars.

That’s according to a report to be released by eMarketer this week, which predicts that spending on podcasting advertising will quintuple over the next five years, from $80 million in 2006 to $400 million market in 2011.

eMarketer analyst James Belcher is betting that a familiar Web power player will spark much of that growth: Google. Belcher expects that by 2008, the company will develop a version of AdSense that can be easily adapted to podcasts, making adding advertising to podcasts as easy as incorporating AdSense ads into blogs.

“That should help grow the market,” he said.

Despite a relatively small base of users, podcasting represents an attractive medium, given its targeting, its low cost and its passionate user base, according to the report. “These people constitute an excellent media target,” Belcher said. “It’s a self-selecting medium. These people are into it, and they’re really into it.”