The Canadian Broadcasting Corporation’s efforts to create a third national radio network aimed at young people and playing the hottest new music seemed to wither on the vine before it even began, but after several years and countless reimaginings (none of which included actual radio broadcasts,) the so-called “Radio 3” seems ready to take off on the wings of the new phenomenon known as podcasting. A partnership with Apple’s iTunes music store, which is driving the podcasting craze, and CBC’s own ability to cut deals with cutting-edge bands, add up to a potentially important new service. Radio 3 will even be getting an actual radio presence this fall, when it launches a channel on the Sirius satellite network.