For some reason, I went to look at Ping on my iPod touch. I was using it as a remote, playing music on my stereo, and I thought I’d see if there was any activity among my friends. Imagine my surprise to find the Ping button was no longer there in the iTunes app.
Here’s a screen shot of the Configure screen, which shows all the available buttons that you can drag to the bottom of the window. As you can see, there’s no Ping.
The way they added the Ping button without updating the iTunes app, and now the way they removed it, suggests that even the buttons in the iTunes app load dynamically, so Apple can make changes any time they want.
It’s entirely possible that it has been removed for some kind of maintenance, or for performance issues. I can’t imagine that they’d be killing of Ping this quickly. It’s odd, though, that it’s just disappeared. It’s still there in iTunes, though.
Follow-up: several people have confirmed that they, too, are missing ping on their iOS devices. Others still have it. Curiouser and curiouser…