The surprise is that it's lasted this long!
Apple announced plans to shut down Ping. Ping must surely be the world's least-used social network, and it suffered accordingly. Apparently the next major iTunes update (tentatively scheduled for this fall) will eradicate all signs of Ping from the iTunes interface, and it will be as if it never happened.
Ping was in theory not the worst idea in the world. It sort of tied into the Genius Recommendations, by giving you a way to build a social network around your musical tastes. You and your friends could recommend music to each other, share playlists, and see what each other had been playing. But from a practical standpoint, Ping was a case of "too little, too late." By the time Apple launched Ping in September of 2010, the majority of people who would be interested in this sort of social networking had already adopted Last.FM, Rdio, Pandora, or Spotify as their platform of choice.
Every form of software benefits or suffers from "the network effect." But social networks literally live or die by the network effect. Coined some years ago, "the network effect" means that the more people use a service, the more people are likely to use a service. You get buzz, recommendations and word of mouth, and the ubiquity works in favor of a service or software.
(Microsoft Word is a great example of the network effect in action. It's not the best word processing program by a long shot, but it's popular because it's popular… to the extent that every other word processing program must be able to handle .doc and .docx files, because that's what everyone sends you.)
Ping also limited users to the iTunes interface, inside Apple's "walled garden." Other music social networks interfaced with Facebook, which made it easy to add your Facebook friends to your music network. Apple's refusal to interface with Facebook made it more difficult to find and add friends, which is pretty much the absolute last thing you want in a social network.
Worst of all, Ping only gave you thirty second snippets of your friends' songs. Most of the other services give you the whole entire song to listen to, streaming free over the internet.
The only surprising thing is that it took this long for Ping to die, frankly.
It's easy to make the jab that Apple failed at making a social network because Apple doesn't see the world as being a social place. Apple has a one-way relationship with its customers, and that ethos is contrary to the philosophy required to build a successful social network.