[flipbrad]

The answer is: Grooveshark routinely has to take down (unlicenced, non-fair-use) copyrighted content, just like the others. That's the cost of DMCA safe harbour compliance.

[stianan]

How come they have so much content then? Is it because the copyright holders can't send them sufficiently detailed take-down notices fast enough?

[kin]

Pretty much. You'll see that the aggressive ones are taken down, like the Beatles, won't find that at Grooveshark. However, you can upload your own Beatles tracks and label them differently "B34tles" and it'll stay up there longer, just like the Kazaa days.