Podcasts may have become mainstream overnight thanks to Apple iTunes, but marketers have to surmount the various challenges - including those related to metrics and fragmented audiences - associated with the novel phenomenon before ad dollars begin to flow, writes ClickZ. It quotes a FeedBurner VP: "The first step in any commercialized relationship is for the content producer and advertiser to have an agreement on the reach of that particular broadcast."

Because podcasts are distributed via RSS feeds, RSS-related firms are helping podcasters to figure out how to profit from their businesses. FeedBurner's technology measures the number of people who subscribe to blog feeds, read a post, or click through on links.

But the issue with podcasts is that once they're downloaded they're no longer connected to the internet and can't be measured online. Apparently, some podcast advertisers are turning to techniques used for - not surprisingly - radio, such as custom 800 numbers or offer codes.