Twitter announced a partnership with Apple this morning that amounts to this: you can now post links to song previews on Twitter from inside iTunes Ping.
Most of Twitter's other partnerships are very interesting. Streamed Tweets on top of Current.tv's live Presidential Debate videos. Real-time search results inside Google and Bing. Twitter-branded bottles of wine sold to raise money for needy children. But Tweeting music previews from Ping? That is not very interesting. Now you can push iTunes ads into your friends' Twitter stream from inside a social network no one uses. That's not exciting, it's depressing.
For a good overview of Ping's shortcomings, see BuzzFeed's post Ping Fail: 5 Reasons To Avoid Joining Apple's Social Network. The long and the short of it is this: the user experience is unappealing and it's totally focused on commerce not community.
In other words, Ping is like the opposite of Twitter. I asked Twitter about this and was told the following: I should have some more coffee (that's true), this feature adds music to the Twitter side panel (but only 30 seconds of it) and Apple has told labels that it intends to expand iTunes previews to 90 seconds (big whoop). So far the music player doesn't seem to work yet, either. Clicking on a shared music link from iTunes launches the iTunes store. No fun.
This is the internet, where if you want me to buy music you're going to have to make it really easy and compelling. This doesn't pass that test in my mind.