I think that this has come up before. All I was able to find from Blair on the topic was "Multiple players controlling the same units is a possibility." Soooo, if you keep crossing your fingers really hard it just might be in there.

Yea having two people control an empire opens up a lot of possibilities, but then it could also lead to conflict as the players might not completly agree on each others actions.

no multi player control works great typically you do a gentlemans agreement as to who does the "opening phase" - Starcraft had this feature and it worked well it just never grew to popularity as I don't think people knew about it (its the TEAM MELEE games) I found it was a great deal of fun at lans so you and a freind could team up against 2 other people... lot of fun.

I don´t have any experience in Real Time Multiplayer, but I think in an "epic" game like this, being able to assign, for example Fleet Admirals and Planetary Governers could be cool (would likely only work for LAN).

Imagine 2 teams of 4 to 6 players each, each player controling a TaskGroup of several fleets or a group of planets. They might even be getting orders from High Command)

Just a shot into the blue

Ahaha ,in no offense to spikyzero, but clam v clan?   just made me laugh, i know its a minor typo, but i laugh easily. Anyways, i think that this game will be a lot more diffrent from Starcraft and how many people will really play the gentlemanly way and actually agree on things. No, i think that there should be a rank system that would define who has ultimate authority over what inside a game.

Some thoughts about this...

Obviously, having two people control the entire empire at the same time is doomed to failure. You'd have planets attacking themselves and fleets trying to go in two directions at once. It'd be chaos.

However, it might work (and would be very cool) if you designated one player as the "Leader," and the others as his "Admirals." The Leader controls the entire empire and can give orders to anyone, but he can also assign control of specific planets or ships to his Admirals, who would then fight battles and manage planets for the greater good of the empire. For example:

Emperor Fred, Leader of the People's Democratic Republic of Fredland, has a massive empire that spans two galaxies. He is at war with two other, similarly large empires - the Kingdom of Andromeda and the Earth Federation. Obviously, despite being a god in human form, Fred cannot be expected to manage all the Happy Free Slave Worlds of his Republic and fight two major wars all at the same time.

Fortunately, Fred is not alone. Under his command are the daring Admirals Bob and Steve, and the slightly-less-daring Admiral Mike. Admiral Bob is assigned control of the forces assigned to fight Andromeda, Admiral Steve is placed in charge of conquering Earth, and Admiral Mike is left with managing the Happy Free Slave Worlds, while Fred coordinates the offensive.

I like the story you put in Arilias   
But i think your idea can be improved upon, i think that they should just have divided jobs the "Leader" would be the only one making the fleets and managing the planets, while the "Admirals" would manage space battles and the conquest of new worlds. Ofcourse the "Leader" should be able to give complete control of certain worlds to his "Admirals", but if they misbehave, then off with their heads!!

Yes the transferring could work. But, as of now i dont know if we actually get allies in this game. I know we can create peace agreements and coduct other forms of dimplomacy but that doesnt mean that a person that at peace with you will risk going to war for your planets.

Various Roles ive just thought off

Offensive Microer - controls invading fleets and plantary assualts
Defensive Microer - defends against invading fleets and uses weapons platforms

Economic Engineer - Controls development on planets and space resource units
Fleet Engineer - Controls the building of fleets, retirement of fleets and assignment to the microers.

Strategical Overseer - Keeps zoomed out , advises microers where to hyper to and from.
Tactical Overseer - Analyses Enemy tactics and advises on intelligence and scouting.

Supreme Overseer - Gels the team together and has final call on the key decisions. Acts as a diplomat sorting trade alliances and bounties.

Yea i mean i would get bored staying just in zoom and saying "hyper space into x" and such.

I think the key to making coop style mp or even LAN work well is for the Game to actually Acknowledge the Role a player takes within a team. I think this is very important because players can get pissy with each other and try to take over each others role unless theres something official set in stone.

Even if its a simple change of palatte for the UI or just a tag saying "Defensive Player" or "Eco player" it would make coop work.

I for one enjoy playing co-op more than any other form of play. Ever since I saw the Two-people-on-the-same-team mode in Starcraft I've been wanting all games to have that option. In games that have a single player campaign and multiplayer modes, it'd be great to be able to go through the campaign with a buddy on your team if you want. Total War: Medieval II is a great game, but I can't recommend it to one of my friends because he only plays multiplayer and there's no multiplayer campaign mode in it (I'm really hoping they'll add that in an expansion. I'd buy it in a heartbeat.).

Anyways, I really hope they have this feature in Sins of a Solar Empire. I would really like to be able to have friends jump in to help out. Hopefully they could join a game already in progress, but if that's not possible then just having friends on the team would be great. Having some type of "Job Position Tree" or whatever you want to call it, where the Emperor is on top and can create positions below him/her and assign assets to those people would be awesome for a game such as this as well. Each of those people could then be able to create positions beneath them, but could not affect the positions of other people on the same row or above themselves. A person could then be assigned some existing ships, maybe one or more planets.

I don't think backstabbing would be a big issue as some people on here have been saying. It simply needs to be impossible to attack ships and planets of the same Empire.

See its not that kind of backstabing im personally worried about, say player x gets pissed at player y for whatever reason, and they are both playing co-op. Now player x sees player z(the enemy) massing fleets towards one of his planets, so he asks player y for some ships to help out the entire empire. However, player y is immature and doesnt want to forget their earlier conflict, so instead he keeps his ships where they are and watches player x strugle.