Hemispheres says:

"We prohibit the use of electronic simulated somking devices (cigarettes, pipes, cigars, etc.) on our flights."

Too bad they don't prohibit chewing tobacco, too. I had a totally unpleasant flight recently sitting next to a jerk who was cursing me (after I booted him from my seat he poached) between brownish spits into a 20 oz. soda bottle.