The key virtue of traditional radio is its immediacy: the fact that it's live. They key virtue of this new breed of radio is that it's Net-native. That is, it's archived in a way that can be listened to at the convenience of the listener, and (this is key) that it can be linked to by others, and enclosed in an RSS feed.
It's because of that last feature that Adam [Curry] could create iPodder, which automatically routes a podcast to an iPod (it's what Adam calls "an iPod filling station"). Note, as I said Sunday, that this does not need to be limited to iPods. iPodder is just one implementation that addresses the device that has become the modern equivalent of the transistor radio (the first truly personal portable radios, which not coincidentally made rock & roll happen in the 50s and 60s).