Disclaimer: I have no idea what I'm talking about.
I can imagine a sort of chat facility being somewhat interesting, with audio and video for those who want to use it. Imagine that whenever you have the "ChatMFD" active, you are given a list of orbinauts/ships and their distance (or light-time) from you. They don't have to be at the same MJD as you, just "in the neighborhood". You can hail one (or more) and exchange pleasantries, technical details, opinions on nearby watering holes, etc. Maybe you can show your face (especially if you have a costume or simpit), or speak in real-time (if not too time-lagged).
This isn't quite multi-player, since there isn't any play, but it might add a social dimension currently lacking, for those who want it. Eliminating the time-sync requirement makes the implementation nearly as simple as an IRC chat. Of course, people might be talking about two planets near to themselves, when each is only near to one orbinaut, depending on their MJDs. That shouldn't adversely affect social interaction.
Building on this capability, the ability to sync the MJD and other aspects of a scenario among two (or more) ships could enable orbinauts to fly cooperative (or competitive) missions in a common world, such as maneuvering near the ISS together.
These two steps toward multi-player are a far cry from what some have proposed, but the "real world" (even in simulation) will always constrain what we can do. I don't think either of these capabilities would require much in the way of a central server, other than maintaining a list of who's online and where in the universe they are. The rest would probably be peer-to-peer.
Does this make any sense? Appeal to anyone?