When I was in elementary school, kids walked around the schoolyard with their miniature boomboxes blasting whatever they could get their hands on. They sat on the steps showing off cassettes, unfolding liner notes, and talking about which band was better. Half of the music I still listen to today came from those recess hours, and I’d never have heard it without them.

Music has always been social. It starts both friendships and arguments, and is a huge piece of everyone’s identity. When you think about it this way, Ping seems like something that should have happened years ago. It’s already a “can’t remember life before it” feature.

What took them so long? For starters, Ping, like most social networks, has a huge potential for chaos. There are (as far as I can tell) no moderators or editors. Users do and say what they want, to whom they want. They may say things that have nothing to do with music. They may complain about iTunes, or Apple, or other Apple products and services. They may give the service a life of its own that nobody envisioned. Aside from being hosted on Apple servers, Ping’s core content appears to be largely out of Apple’s hands. It’s a leap of faith for a company that’s used to being in complete control.

That said, it probably did not take long for Apple to realize it had a hit on its hands. I suspect Ping has already more than paid for itself through new music that people were not going to buy last week, and now have.  As the iTunes catalog gets bigger, it gets harder for you to find something really good, and much harder for Apple to bring you to it. The truth is, no amount of metadata or algorithms will ever beat “your best friend loves this.” (Are you listening, Google?)

It’s interesting how much more polished the Ping UI is on iPhone than on the desktop—a testimony to where Apple thinks the money is. Whether you’re standing in line, sitting in an airport, or on the bus, Ping will help you find music with more confidence, and in less time, than ever. The desktop UI, by contrast, looks horribly rushed, and not nearly up to Apple’s usual standards for a demo, let alone a shipped product.

Was there any urgency? Hasn’t iTunes been just fine as-is? Yes, but it had pretty much run out of tricks. I suspect someone at Apple finally realized how lucky they are that Facebook hasn’t started selling music yet. 500 million connected users talking constantly about what they do and don’t like, even “Liking” official band pages and sharing videos. The only missing piece is commerce. Is Ping a threat to Facebook? Not really. But Facebook Music would be a massive threat to iTunes. By striking first, Apple doesn’t need Ping to be amazing on day one; just good enough to make would-be competitors think twice.

I’m already buying more music. I shudder to think what will happen once we have Ping for books and apps.