We've just received a tip that an iPhone radio.app is being developed in-house by Apple for use on the iPhone and iPod touch. From what we know, the app will be allowed to operate in the background like iPod.app and will offer the same functionality as the FM radio in the new iPod Nanos.The source mentioned that this application could also be incorporated into the iPod.app before release.
The holdup on this app is that Apple is trying to integrate the Mobile iTunes Store purchases into the functionality of the program. For instance, if you like a song you are listening to on the radio (and that station supports tagging and you are in the US), you will be able to push a button and see the song (and all of the information around it) in the iTunes Mobile store. With another click, you'll be able to make a purchase. This is an extension of the Song Tagging feature used in the iPod Nanos. Perhaps they could even add some Shazam technology to help with those stations that don't support tagging.
Though it wasn't specified, the app will likely have the same Live Pause functionality that the Nanos currently enjoy.
Apple's iPods and iPhones have been able to receive FM radio signals for some time now. The latest generation of iPhone and iPod touch can even broadcast FM signal, for instance to a car stereo. The ability of the iPhone and iPod touch to receive FM signals has been used solely in the implementation of the Nike+ ecosystem to this point.
This wouldn't be the first time Apple awoke sleeping hardware functionality from its mobile products. Apple sometimes chooses to leave hardware features dormant in their products until they feel the time is right.For instance, Apple didn't enable Bluetooth in its 2nd generation iPod touch until 9 months after it was released. Apple also hasn't enabled the 802.11N +5GHZ wireless networking (which we also hope to see updated shortly) in its latest iPhone and iPods.
The addition of an FM radio would eliminate that advantage from the ZuneHD over Apple's line of Touch OSX products.
Source:http://www.9to5mac.com/iPhone-fm-app
