Ping, Apple’s fizzling social network, has gained Twitter integration, allowing users to
spam share all their likes, posts, and reviews with their Twitter followers. By default, Ping will tweet all your activity, but this option can be disabled if you want to keep your taste in music private. (Though, opting out of this effectively disables the integration, since you cannot selectively post activity to Twitter via iTunes at this time.) On Twitter, followers will be able to listen to 30 second song previews directly in their news feed, and launch the iTunes store to purchase them.
Apple has been working to enhance their musical social network, but after the initial failure to launch, the service hasn’t been adopted as successfully as Apple may have hoped. They are still pushing for Facebook integration, but it is unknown when—or if—this will occur.
Deeper iTunes/Twitter integration would be nice, such as the ability to click a button to tweet the currently playing song, a la Instinctiv. It seems like Ping is in its own little world within iTunes, and this may be the reason it is not widely used.