Apple are shutting down their music-powered social network, Ping. Apple have announced that they will be no longer accepting new members, and they "thank you for your interest in Ping". This interest just wasn't enough to keep the doors open on Ping.
There's not much else to talk about regarding Ping, as it was nice and short. Ping is shutting down on September 30, and will no longer be available, directly from Apple's site.