Ping, Apple's foray into music-centric social networking, hasn't seen much in the way of updates since it was announced two years ago, and now the folks in Cupertino are set to shut it down on September 30th. Struck with the sudden urge to sign-up for the service and take it for a spin before it goes offline? You're out of luck. Visiting the network's home in iTunes reveals that Cook and Co. are no longer accepting new members. From here on out, you'll just have to find other avenues to keep tabs on what tunes are playing within your social circles.