ESPN has reengineered its streaming radio app to offer improved sound quality, push alerts for when a favorite program is going live and content-caching for listening to podcasts without an Internet connection.

It’s also launching the app for the first time on iPad. The app is already available for iPhone, Android and BlackBerry; the updated version will hit Android in June, and a Windows phone app will be available this summer.

If you vaguely recall ESPN having just updated its radio app, you would be correct: The company retooled it less than 18 months ago to include new search and personalization features, as AllThingsD’s Peter Kafka reported here.

Marc Horine, ESPN’s vice president of digital and print media, says that with the newest version, the network is trying to refocus on what’s most important with a radio app — the listening experience. Files have been compressed for faster streaming and downloading, and the sound quality has been enhanced, Horine says. And the app includes DVR — which allows users to skip ads, by the way, though I doubt ESPN would encourage that — and the ability to download full podcasts for listening offline.

Most of the content on the app is commentary, though there are some live play-by-play game options, and there’s a SportsCenter update available every 20 minutes (for the really, really rabid sports fans). To lure listeners to the app, ESPN has mixed up its app offerings to include original, app-only programming with stuff that’s already broadcast on terrestrial radio, like “BS Report with Bill Simmons,” “Pardon the Interruption” and “Fantasy Focus.”

At $4.99, the new ESPN Radio costs two dollars more to download than the old version, and runs in-app ads as well as commercials throughout the podcasts.

Horine says the mobile radio app has been downloaded more than 740,000 times since it first launched two-and-a-half years ago. That’s actually a pretty small percentage of the 24 million weekly radio listeners ESPN claims across all platforms.

And the majority of listeners — 90 percent, Horine says — listen to radio while at work Monday through Friday. But now, with the ability to stop and start radio podcasts on your desktop and pick up right where you left off on the mobile app, ESPN envisions mobile will become a growing fraction of those listeners.

(Full disclosure: I worked as a non-Disney employee for ESPN from 2003 to 2006. I was not involved with network’s radio programming.)

Does that sound like progress to you? It should.

That’s because Carolla’s old gig, which ended in late February when CBS Radio (CBS) pulled the plug on his show, made him just another guy trying unsuccessfully to fill Howard Stern’s shoes.

But the comedian’s podcasts are something else, and they don’t sound like anything else on the radio: Unedited, rambling conversations with a single guest that often sound more like monologues than an actual interview. They’re profane, they run an hour or more, and they make me laugh out loud. (You can get a small taste of what they’re like via the video clip at the bottom of this post. Be warned: There is a smattering of R-rated language in that one).

I’m not the only one. Carolla has been podcasting every weekday for the past month and a half, and an average show finds an audience of about 400,000 people. His most successful ones have nearly doubled that total.

That’s nothing compared to his last radio job, which was broadcast out of Los Angeles and syndicated in a dozen other markets. But in the world of podcasting, that qualifies as an instant hit, and it’s enough to keep his show at or near the top of Apple’s (AAPL) most popular podcast list at its iTunes store.

The other top podcasts, by the way, are all spinoffs or repackagings of shows made by big media companies–NPR, Time Warner’s (TWX) HBO and Discovery Communications (DISCA). But Carolla’s show is created from scratch: It’s just him and a handful of assistants who help him record the show and upload it to the Web. He started off taping the shows in his house in the Hollywood Hills; now he’s moved it to a garage he rents in an unlovely industrial stretch in the San Fernando Valley.

All in all, Carolla estimates he’s spending about $3,000 a month to produce the show, primarily on bandwidth bills. Revenue: Zero.

That’s primarily because Carolla can’t make any money from his show until the end of the year. He’s still getting paid–very well–by CBS, and his contract has a noncompete. But it’s also because it’s unclear how Carolla could actually go about making money from his podcast even if he wanted to.

The basic options: Try to charge his listeners or try to sell advertising. The former hasn’t been done before, and the latter hasn’t made other podcasters much money so far.

“I think that he’s going to have a tough time,” says Marc Horine, VP at ESPN Digital Media, who oversees a stable of podcasts that were downloaded about eight million times a month last year. Even at that volume, Horine says, ESPN has only been able to turn that into a “7-figure-plus” business–and that’s with a large sales staff and the ESPN brand name.

The problem is that podcasts are still considered “experimental” buys for advertisers. And until podcasts can aggregate bigger audiences–and provide marketers with better ways of tracking their ads’ performance–they are probably going to stay that way.

But I’m going to be slightly more optimistic than I usually am on this one: I think that Carolla’s profile, combined with a dedicated audience, could convince a handful of advertisers to take a flyer and sponsor the show. That still won’t come close to replicating his radio money or the money he’ll make if CBS decides to pick up the sitcom he’s working on for the network.

But as Carolla notes in the interview below, entertainers don’t have any choice but to be on the Web. And figuring out how to make good stuff people like is much harder than figuring out how to make money from it.

Apologies for my stammering and stumbling midway through this interview, by the way: Sounding cogent while you ask questions is a lot harder than it looks.

And here’s a sampling of what a Carolla podcast is like: A snippet of his recent podcast with writer Dana Gould. Again, be warned that there’s a light dusting of cursing here.