There are a few podcasters that were doing this before it was called podcasting. The most obvious in my mind is the long-running Linux Link Tech Show. Linc, Pat, Dann, and Alan are about to produce their 150th weekly show which they've been streaming and later offering as podcasts since the beginning of time. Blog Talk Radio is one of those things that doesn't being anything really new to the table, just the ability for more people to participate in it by lowering the technological barrier to entry much like Blogger did for blogging.
Gizmodo seems to think that the time-shifted nature of podcasting is a weakness which a service like BTR can eliminate:
I have to wonder about that, though. I mean, the time-shifted nature of podcasting really gives the podcaster and listener the best of both worlds. Both parties can do their bit of the process in their own time. Kelly Penguin Girl and I, for example, routinely record our shows on Friday nights. That works well for us, but it's not a popular night for many of our listeners to sit at home and listen to the show. We've also done a few mobile casts when we're driving across country (and going to be doing another one shortly) which is only possible because we can record when we like and our listeners can download it when they like.
Interviews are another matter. Given than we live on a global Internet, timing interviews that work well for all parties is a challenge. I've heard many a guest in Europe on The Linux Link Tech Show grumbling that it's 2am their time.
Further, an awful lot of podcasters post-produce their shows. Anyone who uses Audacity (which is an awful lot of people) knows that you can't cue tracks and have to insert bumpers and promos either by stopping the show to put them in, or insert them in post-production. That's a tough task on a live show.
Lastly, a comment on the Blog Talk Radio website itself. Each podcaster has the ability to pump in their upcoming show lineup so interested listeners can see when they'll be recording. Listeners can also tell the site to send them a reminder email. Good stuff, but I don't see anywhere what time zone we're talking about. I can see that the So-And-So Show is going to be on tomorrow at 9:30, but I don't know in what time zone. Seems like an obvious thing that I'm sure will be fixed soon.
I'm admittedly curious about streaming a live show and taking callers and I've blogged as much before. I'm not against the idea at all, but I am against the idea that the pre-recorded nature of podcasting is a weakness in the genre. It is decidedly one of its greatest strengths