Like many people since last weekend I’ve been bingeing a series since last weekend. No not the new season of House of Cards, although I will be catching up with that very soon, but Alex Blumberg’s Startup podcast about how to build a startup podcasting company. Very meta.

It’s been sitting there on my phone for many months, unlistened to. But I was pushed into listening after I listened to a recent Slate Money – possibly my favourite podcast right now.

Slate has been busily developing a burgeoning podcast business. Although they’ve been making podcasts for a long time now, in the post-Serial world, things are really taking off. The high CPMs (cost per thousand – the rate that advertisers pay) that podcasts can charge advertisers, the spin-off live events, and the flexibility that audio offers are all being snatched up.

Andy Bowers runs Slate’s podcasting business, and he was on this episode of Slate Money talking about their new “platform” – Panoply. They’re partnering with a number of blue-chip podcast providers with some big names like The New York Times Magazine and Huffington Post, to provide facilities, editorial support and I suspect mostly, advertising sales.

They’ve built a strong podcasting business, but this perhaps allows them to scale it more, and drive listening.

[Side note: I’m not sure about the word “platform”. I think of platforms as new or bespoke technologies. If they were removing mp3 versions of podcasts and using some new technology that embedded imagery, provided metrics about how much of a podcast was actually played, or other “beyond podcast” technologies, then I think “platform” would be right. In reality, I think this is a “podcasting network.” Your mileage may vary.]

And they’re not the only ones. There’s the “Startup” business that has been honestly documented in the podcast I’ve just been listening, and there’s mighty Kickstarter success, Radiotopia (who recently published some interesting numbers about their success to date). Beyond that there are a myriad of different networks of different sizes and specialisms out there.

These would seem to be good times for podcasters.

But I’d like to see more brand advertising on podcasts. The advertisers I’ve personally experienced so far have been direct response advertisers – enter a coupon code for a free trial or money off. So I know all about Audible, Square Space, Mail Chimp and Harry’s – which isn’t even available in the UK. But I’m hearing fewer advertisers who are building brands over the longer period – “You might not be buying a car now, but next time you do, you’ll want a BMW,” or “Why not try our new flavour of Coke?” Neither of these are transactions that you’re likely to complete online. Yet a vast amount of advertising is actually this sort of thing. It’s not trackable via entering a discount code on a website. It just plants the idea that next time you’re thirsty, you’ll drink a Coke rather than a Pepsi.

To help achieve this, another interesting development is that Triton Digital and Edison Research are launching metrics for podcasts. They claim that it is to precisely support this kind of advertising model than big brand advertisers need (they get it from their other media).

Triton and Edison’s aims are bold, and to be welcomed. But I wouldn’t under-estimate the technological challenges of this. The RAIN article above says that there’ll be a combination of client and server side measurements. This suggests perhaps a panel with an apps on their phones or computers to measure listening, allied with data supplied by the podcast providers. Neither is a straightforward task, and the latter suggests that only providers who sign up with the pair will be measured. (Ordinarily you might measure the non-subscribing outlets, but just not publish the data to give them a free ride).

All of this raises a few questions for me:

For these businesses to scale, podcasts need to be made easier to listen to. What are they doing to achieve that? And as I mentioned the other day, there’s the Android problem. Is there an over-arching technical solution to this? A way we can listen on a multiplicity of devices, and importantly, share that audio with others. I’m convinced that shareability is key to podcasting’s growth.

Much of what is happening is, by and large, all happening in the US. What about the rest of the world? Yes, in the UK we speak English too, but there are only so many US political gabfests or whatever that I want to hear! Podcasting is still really driven by radio broadcasters, and the BBC in particular. Crowd-funding notwithstanding, I’m not sure that there is quite the range of advertisers buying into podcasting in the UK or elsewhere in the world, as there is the US.

So the common theme, if there is one, among these developments is that these new businesses are all coming from an NPR background. Does that impact on NPR’s audiences in the longer term? At the moment many of the big podcasts air on NPR stations, but over time that will change. And the NPR audience (or Radio 4 in the UK), is only a fraction of the audio-listening audience. Yes they are wealthy, which is why everyone is clustering around them, but true scale is going to be achieved via mass-market. Who’s targeting the wider population?

I’m excited about the future of podcasting, but I wouldn’t pretend that there aren’t some big challenges.

In particular, I’d like to see more non-broadcaster activity in the UK. Audioboom has made some movements in that area, with its recent deal with Russell Brand (ironically then getting a broadcast on conventional radio via Xfm). But it’s not clear to me yet what Audioboom’s business model really is. It’s certainly changing though.

Then we had The Guardian pull out of a lot of podcasts last year, just around the time that the US podcasting boom was underway. Will they re-evaluate a bit? I note that they’ve just launched a Startup-style behind the scenes podcast documenting an attempt to properly engage the public over Climate Change.

And podcasts are certainly feeding back into radio. According to David Hepworth in his Guardian Guide radio column this week, Radio 4 is looking for its own version of Serial, although it may not be offering quite the same budgets as that series had. At an event at the BBC Radio Theatre earlier this evening, The Media Show’s Steve Hewlett asked Dana Chivvis, producer of Serial, how much it cost. She didn’t know, or wouldn’t say, but spoke of at least two full-time salaries for 15 months plus more production costs – including her own – beyond that. It was not cheap, and they were fortunate to have the backing of the behemoth that is This American Life, even if at 6 million downloads an episode, it has now overtaken its mother-brand.

The really interesting thing is just how important audio remains, with so much of what’s happening in technology revolving around it.