There is a big rant exchange going on over music encoding schemes (WMA, AAC, MP3), DRM, and degree of choice. It all started with Robert Scoble and then bounced all across the board touching off iPod fanatics, Microsoft hater, and copyright guerillas.
As for me, I don't think music encoding scheme will matter in the future. I think market competition, consumer activism, and hackers together will eventually force online music services to provide a token of ownership for each music one buys, a token that can used to get same music encoded in a different format.
Anything else will be as attractive as going to a underground disco without fire escapes.