Thirteen of the 100 most linked-to podcasts fall into Apple's "explicit" category, making erotica the most popular form of podcasting, and giving rise to a subcategory called porncasting, or podnography.
"Is it surprising? Absolutely not. It's inevitable," Gartner2 technology analyst Mike McGuire said. Any time a new technology becomes democratized, McGuire added, sex is bound to find its way into the mix.
Listeners can download porncasts to their iPods, MP3 players, cellphones or computers for free. Content ranges from video reviews to naughty stories to interviews with porn directors and stars. And listeners apparently can't get enough.
According to business and technology consultant Alex Nesbitt of Bella Ventures, "the supply [of risqué shows] is not yet meeting market demands," a fact that has created a significant market opportunity for content such as adult industry-focused talk show reviews of adult websites.
Suicide Girls, Violet Blue
A smattering of industry professionals already are taking advantage of the new medium, including SuicideGirls and web mistress Violet Blue, whose "Open Source Sex" program was iTunes third-most-downloaded during the month of July.
Because podcasts are sent out over the Internet, they are not subject to Federal Communication Commission regulations. Apple allows adult material; it simply asks producers to label such shows "explicit."
In other words, anything goes, making shows such as "Fetish Flame" and Blue's "Open Source Sex" popular fare.
"It's really a blast; I get to say all the things I could never say on FCC-controlled radio," said Susie Bright, editor of the "Best American Erotica" book series and producer of a podcast called "In Bed With Susie Bright."
According to Bright, it's only natural that porncasts are popular among fans of adult entertainment because they share many of the same elements that made Internet erotica so successful — namely, voyeurism and anonymity.
Some people like to eavesdrop, as if you're in a motel room and somebody is screwing in the next room," she said. And there are none of the worries that typically accompany other forms of aural erotica, such as the per-minute charges and permanent records associated with phone sex.
The main appeal for porncasters, on the other hand, is complete freedom.
"I don't have to censor my language or anyone else's language," Violet Blue recently told the Wall Street Journal of her podcast.
"It's like the dog is off the leash," she said, adding that her goal is to "be as indecent as possible."
But Nesbitt said the majority of porncasts currently available aren't being put out by pros like Violet Blue. Instead, they are fairly low-quality. In most cases, they are put together by inexperienced enthusiasts using cheap equipment, such as Gray Dancer, a Wisconsin resident whose "Rope Weekly" show about bondage is "a labor of love."
But even these amateurs are drawing an audience — "Rope Weekly" brings in 500 regular listeners — which hints that savvy producers could reap the rewards of offering more polished products.
Although podcasting is uncharted territory for advertising, some producers are experimenting with advertiser-sponsored shows to generate revenue.
SSL International, maker of Durex brand condoms and lubricants, recently contracted with Dawn Miceli and Drew Domkus, a married couple who produce "The Dawn and Drew Show," to plug its products for 10 episodes.
Another enterprising podcaster, Virginia Bytheway, earns commissions by driving listeners to a website.
While there's no way of predicting whether such a business model will work, the risk to producers in terms of financial investment is minimal because producers can submit their shows at no charge to Apple through iTunes.
But there are potential risks of a different variety since podcasting also is uncharted territory concerning obscenity. Programs can be downloaded by listeners of all ages, labeling of content is voluntary and there are no guidelines regarding what is explicit and what isn't.
At a minimum, one has to imagine a public relations backlash from the usual suspects on the extreme Right can't be far off, let alone a coordinated attack from more official quarters.
Widespread media coverage of the burgeoning medium also has put Apple on alert.
"Apple needs to be careful to protect its brand here," Forrester Research analyst Ted Schadler recently told the Wall Street Journal, prompting Apple CEO Steve Jobs to stress that the company does not accept pornography.
Such statements have some podcasters worried that, just like most fun adult activities in the land of the free, the days of uncensored porncasting may be coming to an end.