Heard Jeff Black on NPR this evening. He is already using podcasting to distribute new music every week. This model explodes the frequency of even an Ani DiFranco who puts out a new CD every year as well as bootlegs every few months.
Black's music was pleasant and interesting to listen to -- as professional as almost any other singer/songwriter I have listened to. Only because he is using the technology medium to reach new people, which made him interesting to NPR, did I hear of him.
The NPR page has links to several songs as well as to more information about podcasting.
On the other extreme, Jane Siberry now sells all - ALL - of her music via downloads. No more CDs, no more cassettes, no more physical inventory.
I predict that more leading edge singer/songwriters like DiFranco will start creating and distributing podcasts.....soon