Just bumped into this July 17th post. More bang for the Premium/Business bucks, in the form of scheduled social media posting of new (or old!!) WordPress.com content. Neat-Oh!
The new Advanced Social Media feature for Business and Premium plan users (and for Jetpack Professional and Premium users) lets you schedule specific times that your content will be automatically shared on places like Twitter, Facebook, and LinkedIn. You can also preview your social updates before sending them, so you know exactly how it will look when it goes out.
I wondered how this new addition interplays with the automated Publicize feature. Short answer: controlled through the Sharing menu on the posting screen. Details: https://en.support.wordpress.com/publicize/