I'm going to play devil's advocate here, not just for the sake of argument, but because I feel there is a fundamental flaw in the attitude of some of us using an e-cig/PV. A quick analogy: I can fart or burp or laugh loudly in public, at any time. There are no laws that specifically forbid such behavior, but is it appropriate to fart/burp/laugh loudly anywhere, at any time? If you were eating at a restaurant, would you consider it ok for me to walk up and fart near your table? There are no laws that specifically forbid it, and if I continued such behavior you'd probably take action against it.
Just because you can use an e-cig anywhere, doesn't mean that it's always appropriate to do so. Not going to lecture much on common courtesy here, but it seems that some of you guys feel a sense of entitlement to vape anywhere, at any time and get some sense of satisfaction for doing it around those that disapprove of it.
It may only be "water vapor" that you exhale, but people can smell it. It'd be like eating at a restaurant while someone next to you sprays, continuously, excessive amounts of perfume on themselves. It's not illegal, but it sure would be annoying.
I love vaping, I'm glad I quit regular cigarettes and wish my cig smoking friends would switch as well. I don't need to tell you guys that the anti-tobacco elements in the US can and will act to outlaw anything tobacco related, lets not fuel the fire. The last thing we need is some heavy-handed law coming down on e-cig usage.
Be smart, be courteous, no reason to fart at the table just because you can.