An article in the New York Times explains the companies plans to raise the prices of more popular songs and lower the prices of less popular songs. They also said some songs will not have Digital Rights Management, which creates a lock on songs so they can not be shared illegally (so they say).
I'm not sure if this is good or bad. I don't think it's fair to have some people pay more (and some artists receive more) because they are more popular, especially if this is because they have better advertising and a more ferocious label. Either way, it's progress in a long battle Apple has been fighting against raising its prices.