I've recently openly (brazenly!) vaped right the way through Irish and UK airports. I certainly got double takes and stares from security, staff and the public, but nobody said anything. Quite a few celebrities have been photographed satisfying their nicotine needs, in airports, with e-cigs, on this side of the Atlantic, so that, combined with members of the public following their example may have raised awareness.
Having said that, someone this year in the UK, attempting to stealth vape on a bus, caused a fellow passenger to fear the use of a biological weapon. The frightened passenger phoned it into the police, who closed the motorway on which the bus was traveling and moved in with an armed response and air cover!!!!!
Sort of a worst case scenario for the stealth vaper....
http://www.guardian.co.uk/world/2012/jul/05/m6-coach-passengers-evacuated-police