The world’s largest broadcaster, Clear Channel, has released an application that turns the iPhone into a radio tuner, allowing the user to listen to a growing number of its stations around the country. The iHeartRadio app is fast, sounds great and is free to download on your iPhone or from the iTunes Music Store. Combined with AOL’s app, which features stations owned by CBS and the previously mentioned Minnesota Public Radio app, the iPhone is quickly becoming an excellent replacement for most portable radios.

The internet has long represented a threat to terrestrial radio, with a seemingly unlimited supply of every kind of audio programming from spoken work to niche formats that have such small available audiences, they simply aren’t sustainable on the local level. But now, as the iPhone moves into pockets, purses and belt-holders all over the world, Radio is wasting no time making it a distribution platform. Clear Channel created the online radio portal iHeartRadio.com to bring the internet streams of the company’s radio stations together on one site. The iHeartRadio app currently streams 20 Clear Channel stations and that number is growing.

The effort is far from wasted, as the iHeartRadio application quickly became the most downloaded app at Apple’s iTunes Music Store. So now, that person with the white ear buds listening to their iPhone or iPod Touch may well be listening to a radio station.