BlogTalkRadio lets anyone host a live radio show with call-in capabilities and up to 2 hours of talk time for free (though shows are scheduled for 15, 30, or 60 minutes). Hosts are assigned two land line phone numbers: One that they call to actually record the show (this can also be done via VoIP, but Levy told me most most people prefer phone) and another that listeners or guests use to call in to the show. Hosts have a control panel that allows them to put callers on air, mute or hang up on them.

From an end user perspective, the technology is pretty simple. Hosts can schedule their shows up to one month in advance and listeners tune in live from the BlogTalkRadio site, from a widget embedded anywhere the host wants, or download the archived show later from either the show's profile page or via iTunes. Listeners, guests, or co-hosts can use a regular land line phone to call into the show, and up to 15 callers can be in the queue at once (with 5 on air simultaneously -- making a Howard Stern-style team show very possible). Shows can have unlimited listeners (in fact, I was told thousands tuned in to hear Oscar-winner Jennifer Hudson earlier this year).

In its first year, BlogTalkRadio has streamed more than 17,000 broadcasts from greater than 7,000 hosts. They now average 170-200 shows per day, with 20 on air at once at the busiest time of the day. The service hosts shows on just about everything you can think of, with the politics and entertainment categories being the most popular. Levy thinks BlogTalkRadio is important because it gives anyone a voice. "It's not one Rush Limbaugh, it's thousands of people out there who have a platform," he told me.

Earlier this year BlogTalkRadio helped make headlines when a campaign launched in part on a show hosted on the website prompted fans irate over the cancellation of CBS television show "Jericho" to send 40,000 pounds of nuts to CBS. The effort paid off, and the TV network has decided to bring the show back for another season.

Right now, BlogTalkRadio is focused on their free service, but in the future the company has plans to offer a premium upgrade that would allow a dial-out service and a way to screen callers before putting them on air. Further, Levy has plans to build a social network around the BlogTalkRadio content. Users will be able to interact with hosts and with one another via profiles, chat, and messages.

Those familiar with the ecosystem of Twitter tools may have already come across BlogTalkRadio in another form: they power the backend for the call-in service of Dave Winer's TwitterGram app.