I loved this article. It covers how a website can start with no clear vision and have the social community direct what it ultimately becomes
They also have a pretty positive outlook on their biggest competitor, Pandora, who they also see as a friend in spreading their products reach.
It's a good realization of "release early and iterate." Provide something good for your users and then listen carefully to what they have to say. That's way, way better than hiding in development for an overextended period, hypothesizing -- without foundation -- what new features are needed.