I personally think we are stuck in a transitional period between traditional music and digital music. The traditional sense of what Amazon is doing is completely illegal, when you upload a file you are technically making a copy of it which technically you could share with others. In a traditional sense all these services are illegal in some respect.
We need new legislation that has clear guidelines. We need a clear way of letting these companies legally share music. There should be a clear port of call for all music providers such as these to try and make a go with their products.
I think they are spending too much time fighting these companies and telling them they are wrong rather than guiding them in the right direction.
I may be way off mark here but as a developer I would not touch anything to do with music licensing again. I really feel for Grooveshark, I have used the service and it looks like they have put their heart and soul into that product and instead of a great big "Thanks for helping the music industry", they get kicked.