The really dangerous thing about exploiting the safe harbor provision like this, where you know that almost 100% of the content is infringing, is that it may ultimately provoke legislators (puppetted by the RIAA and other industry groups, of course) to modify the safe harbor provision in a way that is much less tolerant. That is the biggest reason what Grooveshark is doing is a no-no; they're going to spoil it for everyone else.