Ping integration. Basically, any of your Ping activity (posts, purchases, likes, reviews) can be tweeted, all it takes is linking your Twitter account to your Ping account from within iTunes. Unfortunately, right now it looks like the Tweets are an all-or-nothing affair (you don't get to choose which aspects of your Ping activity you want broadcast), so get ready for everybody to know you bought that Colbie Caillat album. The good news on the Twitter end is that Ping tweets will include album art and song previews right from the fancy new Twitter UI, along with a purchase link, of course. Can you taste the synergy?