Imagine if pirate radio stations were suddenly given prominent frequencies on the FM dial, or if video artists and amateur moviemakers got their own cable TV channels. They’d gain both instant access to much larger audiences and a big dose of mainstream legitimacy. That’s exactly what happened today to podcasting.

Making good on Steve Jobs’ promise last month, Apple released a new version of iTunes and new firmware for certain models of the iPod that give owners of the little white boxes vastly simpler ways to locate and manage podcasts.

I’ve downloaded iTunes 4.9 and have started to play around with it. It’s got exactly the features podcast producers and listeners have been requesting for months.

There’s a one-click way to subscribe to regular podcasts and have them auto-synced to one’s iPod as new episodes arrive. The new firmware (that is, the internal software for the iPod itself) adds a podcasting menu to the existing iPod interface, lists podcasts by episode and date, and lets users create bookmarks within podcasts so they can return later and pick up where they left off. And the iTunes Music Store has a new department dedicated to podcasts, with some 3,000 podcasts listed in its directory.

In my view, the iTunes update is the biggest development in podcasting’s short history since Adam Curry began promoting the medium last year. (More on Curry below, if you want the details.) It means Apple is finally putting its weight behind the new technology and betting on it as a mass consumer medium. For a rough historical equivalent, think of the old NBC and CBS radio networks buying into television in the 1940s, or the flowering of AM music programming after transistor radios became popular in the late 1950s.

Bear with me for a bit of podcasting history. Apple conceived the iPod as its entry into the market for music downloads, and is credited with having figured out a business model (in the form of the copy-protected $0.99 download) that both listeners and the music industry could live with. Given its success in that market, it’s not surprising that the company has consistently packaged the product as, above all, a music player. But in hardware terms, the iPod is nothing more than a high-capacity portable hard drive coupled with a cool interface (the scroll wheel) and an extremely convenient way to acquire content from a PC or the Internet (iTunes). It can carry any kind of content, from audiobooks to photos.

Christopher Lydon, a Boston-area public intellectual with a long background in radio and TV journalism, was among the first to realize that portable digital music players would be a useful platform for radio-style audio blogs. Using code created by programmer extraordinaire Dave Winer, Lydon began publishing his MP3 interviews as RSS feed enclosures in the fall of 2003. (RSS, for Really Simple Syndication, gives Web users a way to aggregate bits and pieces of content, such as blog entries, in a single place for easy reading.) In early 2004, tech enthusiasts began using the term “podcasts” to describe these enclosures. Meanwhile, Lydon’s work helped inspire Curry, a former MTV host with a strong geek streak, to organize the team of freelance developers that created iPodder, a rough early equivalent of iTunes for podcasting. With iPodder, users can both search a directory of available podcasts and set up regular, automatic downloads to their digital players.

iPodder was the key distribution mechanism for podcasting’s first wave – what will inevitably be seen in retrospect as a golden age of amateur audio publishing with shaky production values but refreshing, original, and uncensored content. In less than a year (mid-2004 to mid-2005) pioneers launched several thousand regular podcasts, from the raunchy and irreverent Dawn and Drew Show to the surprisingly hip and candid Catholic Insider, with Curry’s own Daily Source Code as the movement’s central ministry and clearinghouse.

But iPodder remains a bare-bones program that provides none of the handholding and glossy packaging needed to broaden podcasting’s appeal beyond the early-adopter community. Startups like Odeo and Curry’s own Podshow.com are working on ways to make producing and subscribing to podcasts simpler, but neither company has yet made its software public.

Now Apple – to come back to today’s news – has filled that void with the revamped iTunes. For iPod owners, the new features of iTunes render iPodder obsolete, and would also seem to make other subscription methods unnecessary. It will be interesting to see how Odeo and Podshow react to that; it may force them to focus their services on the production end rather than the distribution end of podcasting. Of course, podcasting isn’t just for iPods – people who want to listen to podcasts on other portable audio players will still need other software to get podcasts onto their devices.

But in one swoop, the iTunes update gives tens of millions of Apple customers one-click access to content that they probably wouldn’t take the time to seek out otherwise. And it clears the way for podcasting’s second wave – which will undoubtedly be more professional and commercial, but may also draw in a much larger community of content creators. That depends on whether Apple makes it easy for creators to distribute their podcasts through iTunes. In new guidelines accompanying its podcast directory, Apple says that submitted podcasts “may be reviewed before being posted” and that it will be especially vigilant about copyright violations, “removing offending podcasts if necessary.”

It must be a bittersweet day for podcasting’s pioneers. The fact that the iPod is now officially podcast-friendly is a huge validation for the medium, which barely existed two years ago and now has the opportunity to reach millions more listeners. On the other hand, Apple’s embrace may induce a bit of claustrophobia. Up to now, podcasting has been a largely underground, garage-band phenomenon. Being integrated into iTunes is the equivalent of landing a recording contract with a global music cartel like Sony-BMG.

Still, I imagine that even Dawn and Drew will learn to cope with having a bigger audience. Domestication is the price of success. As long as podcasting remains an open and unrestricted medium, on a par with blogs, it will still be doing its part to push forward the revolution in personal publishing.

Technorati tags: iPod podcasting iTunes AdamCurry Apple Odeo Podshow iPodder SteveJobs