I love grooveshark, I am a VIP and spend clean over 60 hours listening to it every week. However its not good at finding new music.
Its awesome at having/playing/sharing but no good at recommending. Especially small "local" bands, and off genre artists.
I love grooveshark too, but #4 is really about letting people who spend lots of time on something like grooveshark selecting music earn revenue by sharing the music they've selected.