BlogTalkRadio is a podcasting service (like PodoMatic and GCast) but with a difference: It lets you stream your podcast in real-time, and lets you take telephone callers to your show and put them on the air with you.
It's a just the thing for podcasters who want to add interactivity into their work. And BlogTalkRadio is clever in its implementation: All audio input is via the telephone. Podcasters get a private dial-in number to the BlogTalkRadio service, from where they are streamed out to the Net (and also archived for later replay). Callers get their own number too, and BlogTalkRadio provides a Web-based console that the podcaster uses to control the show.
Like standard broadcast radio, BlogTalkRadio podcasts can be advertising-supported. Audio advertisements are inserted, live, in the audio stream; the host gets a warning on his or her console before the ads play, so he or she is able to gracefully cut to the commercial. BlogTalkRadio will split ad revenues 50/50 with the podcast hosts.
Anything that makes podcasts interactive is a great idea, and there are other tools out there that do this too: See RadioHandi, Skype's Skypecast feature, and Waxxi. My biggest criticism of BlogTalkRadio is its exclusive use of the telephone for the host's input. Founder Alan Levy comes from the telecom industry and puts a lot of faith in the capability of a standard telephone capture and transmit high-quality audio. I'd much rather listen to a podcast recorded on a dedicated microphone, and I think BlogTalkRadio should allow hosts to broadcast from a computer.
But that's a nitpick. BlogTalkRadio allows you to create an interactive live podcast that can be broadcast from any location where you can get a cellular signal. That's a pretty cool thing.