Hmm. Having wondered about the legality of Grooveshark, and found (thanks Norm!) that it's interpretation of legality is somewhat "interesting", I am now wondering something else.
In what way does this differ from allowing people to upload all sorts of music to Youtube? Does that material get taken down, and if so, does it get replaced immediately? Or, is it just that no-one wants to get into a legal wrangle with Google, with all their not-insubstantial resources at their disposal? Hmm again.