According to various reports, Facebook integration was dropped at the last minute. All Things Digital quoted Apple CEO Steve Jobs as saying that Facebook wanted 'onerous terms that we could not agree to".
While Facebook integration is still missing, Twitter integration has arrived. Curiously, it was left to Twitter to announce the arrival of this feature.
Users of iTunes 10 can now link Ping to their Twitter accounts so that a Post, Like, Review, or 'Tell your friends' activity is echoed to Twitter. The tweet includes a link to the relevant item in iTunes Store plus a #iTunes hashtag.
The question is, if what you really wanted to do was tweet what you're listening to (etc), why bother with Ping instead of simply sending a tweet in the first place?