Well said, Coolhand! Woo, ignore Marceng9, if the UN were to get angry about it (which they won't), they can't realy do anything. They can't come and kill you, if they sue you, the case will be trown out of court. And if not, then you could ask them why they aren't suing Wikipedia.
Wait, I'm going to go check
the copyright page for Wikipedia's use of the UN logo... Ok, nothing there, but, I would think that flags, insignia etc are all concidered public domain. Mate, if they get their nickers in a twist (assuming that they even know of this DGIV skin, I would say that they don't even know of Orbiter), you can always take it down.
On an semi-related note, a while ago I spoke (pmed, rather) with DanSteph. He seemed a little distressed that none of these skins were being uploaded on the page he specificaly set up on his website for that. He said that he might even take the download section down off his site if it wasn't being used. I would think that it would be an incredible loss if that happened. Do you think you could start to upload the skins there instead?