environment maps arn't realy a lighting thing, there sort of a cheat reflection, basicly you render a background image to a specal texture and then render that texture in a very specal way across the model, the end result of wich is it looks like a reflection, now it would be posable to render every ship in the sceen to the background image to be used per ship, but this would take a huge amound of power to do, I'm thinking maybe down the line I could implement something that would render one or two close objects for a few polys on a huge ship.
now that all said yes they are calculated per vertex, but there is no lighting going on, it's all UV coordanants being generated by the card based on the position and angle of each vertex and normal.
and looking at a few big ships in game, I'm thinking the background isn't getting put together quite right