I just remembered one of the things I suggested for iTunes when it was released.

Apple allows Morgan to create an iMix and publish it to the world (or just to his friends). So Morgan, in a sense, is doing marketing work for Apple's music store. The one piece missing is incentive for Morgan.

Apple will make money when I buy songs from his iMix. He should get a cut. This was the missing bit in other P to P and online music stores; they entirely missed the network effect and power of distributed, one to one marketing.

Apple seems to have all the tools in place to create iMixes and use them as personal promotion tools (independent artists, etc...). If Apple manages to spread some of the profit generated by the iMixes, they'll have a quite an interesting product.