Nuh Uh:No, Yes.
Although it's still on an experimantalstage, it might work, or it might not. The system would see if the square which the unit is on, or any of the surrounding squares, has that specific resource in your trade-routes (which civ calculates automatically. The only problem is that it won't find them on roads that are under the enemies culture (correct me if I'm wrong, sanrko) and so any long "sieges" of cities are impossible. But on the other hand, isn't this also a good thing? Because if you were deep inside enemy territory, even though you had conquered the land from the army, the local poeple would often harass supply convoys.
Maybe it's possible to make every unit continue the resource-trail, so that if there are 10 units side-by-side in a line, and only one unit is near friendly territory, every unit is adjecent of that resource-trail. Probably not possible, but it's one idea.
LRP: That's actually quite a good idea, but what about the AI?But when the AI SDK is out, this can be brought back up. It would (sort of)be the same as bomber movement in civ2. The movement was 8, yet the range was 16, so it could move for 2 turns (and block enemy troop movement in the process

).