I do not have a fear of heights. I can stand quite still on a high structure and feel fine. What I fear is fallling. If I'm swaying or what I'm in (ferris wheel) is moving I get terrified and elevators/escalators don't bother me.
Oddly enough I tried to cure myself by riding the Reisenradt (sp?) in Vienna. Didn't have a single moment of fear, possibly because the whole "room" was moving. Tried another carnival ride and terror was back.