In the UK I'd say that in lots of non-smoking circles, weed is indeed fairly socially acceptable. Not universal, maybe not even for the majority of people (I've no idea how the figures add up).
But for my company, as an example, if I walked into the office on Monday and said "I had a great weekend, was permanently stoned" (not true!), my CEO would be very critical - to what extent I don't know - but he's already critical of my smoking (he attempted to bribe me to quit with a new coffee machine for the office, which almost tempted me), the rest of my colleagues would have no problem with it, so long as I never did it immediately before or during work. Not only with people who don't smoke weed (possibly everyone in our company I believe) but those who don't smoke cigarettes, too.
But for my company, as an example, if I walked into the office on Monday and said "I had a great weekend, was permanently stoned" (not true!), my CEO would be very critical - to what extent I don't know - but he's already critical of my smoking (he attempted to bribe me to quit with a new coffee machine for the office, which almost tempted me), the rest of my colleagues would have no problem with it, so long as I never did it immediately before or during work. Not only with people who don't smoke weed (possibly everyone in our company I believe) but those who don't smoke cigarettes, too.