I don't know if this fits here, so move it if it doesn't. But it IS a modeling question. So far, all the vehicles have at most, a single turret that is controlled by the driver. Now, is the ability to have secondary/multiple turrets on the same vehicle be controlled by persons other than the driver coded into empires? Basically, it says on the manual that the bomber is to have a defensive turret. Is the pilot then supposed to be looking behind him at pursuing fighters, drop the bombs on the target, AND fly the plane? It will obviously be better to have a pilot AND a gunner AND a bombardier. Other aspects would be the proposed "jeep turret" (jeep-rails anyone?) that were supposed to require a second person, a la Halo. As well as independent mounted MGs on APCs and tanks... etc.
It is possible in the episode 2 source engine, that is all i can say about this topic... besides BOMBARDIERS, READY!
Last i heard the new NF heavy tank is going to have infantry-controllable cannons mounted on the side, but atm it's not supported.