I know this idea has been brought up before, but all those ideas were several years ago by now, and I couldn't find a recent discussion about this.
Imagine having "rooms" within Spotify, where you can listen together, simultaneously, to the same track with everybody else in the room, no matter where in the world they are, and no matter what device they're using. You can step up and join the DJ queue, and all DJs in the room play one track, one after another. The friend feed on the right side turns into a chatbox, and you can communicate and talk about music while listening to the same tracks. Think tuntable.fm, plug.dj, jqbx.fm, ... but right inside Spotify!
I've been hoping to have some social aspect like this within Spotify, and I think this would enrich the community even further. You could create rooms based on genres or moods, and enjoy music together with friends and strangers alike. An upvote/downvote function would keep rooms democratic and true to their respective themes.
The mentioned article perfectly explains the concept and benefits of this feature, please check it out!