The military installation commissaries are doing a deal with my company for desert camo and jungle camo versions of our e-cig...No LED and they requested a non visible vapor option (we're still working on it) as well as a regular cart. The carts will match the camo. Check them out on my profile. The samples just came a few weeks ago. So yeah I am prettty sure the US military approves of e-cigs.
They said that the ember of a cigarette can be seen from a couple hundred yards away, and the smoke can be smelled from a couple hundred yards as well.