iPhoneology : Blog Archive : iPhone Firmware Hints at New Apps, Widgets: "The most exciting of these seems to be the mobile.radio, as it suggests the possibility that Apple may be looking forward to supporting streaming radio or hopefully, an FM tuner on the device."
There is some speculation that this means the iPhone may at some point include an FM receiver - I think that the highly more likely scenario is support for streaming radio over EDGE/WiFi. Considering that the Radio stations that show up in iTunes are really just a selection of SHOUTcast stations, I doubt that Apple is looking to create their own radio programming - but instead just looking to bring a streaming experience to their iPhone consumers.
What would be really interesting is streaming radio support in conjunction with over-the-air downloads. As you are listening/switching stations, your iPhone is tracking what you have listened to, thus giving you the opportunity to click "buy" on any track that you have heard and/or highly rated. The could then download the track directly to the iPhone (and simultaneously make it available in iTunes when you get back to your computer.
If I bought a la carte tracks, I would think that was pretty cool. Cooler yet would be the ability to cache a streaming station to the iPhones hard drive.... RadioTivo, but I find it highly dubious that Apple would ever enable a use case like this that could cannibalize their sales.