What etrang has suggested has been suggested to airlines in the past, we actually had a long discussion about it when I was Cabin Crew. As is fairly obvious, banning inflight alcohol was never going to be an option and we, like every other airline, would never even consider doing that. The reasons for this are fairly simple - number one, why penalise the 99.9% of people who behave normally and enjoy themselves, just so that the 0.1% who don't can misbehave and blame something else for their misbehaviour? Number two, if alcohol is banned inflight, passengers will probably drink more in the terminal beforehand and be far more likely to carry their own alcohol onto the aircraft which they will then drink when the crew aren't looking. This means that the crew can no longer monitor the alcohol consumption of these passengers, promoting a possibly worse situation than we had before...
Educating passengers on the danger of over-drinking inflight has also been mulled over, but it's difficult to see how anybody could do any more than has already been done. While it's horrible to be crew on a flight where you have a drunken and disruptive passenger, you just have to accept that if you carry human's on flights for a living, you will have to deal with this sort of situation from time to time. It is a pain in the a**e and very unpleasant for everybody involved, but I fail to see a better and realistic solution to the problem.
Final comment... Piltdown man - you are quite correct by mentioning that the crew will be very aware who is served alcohol and who is not, it's not a god given right for a passenger to be served and it is entirely at the crew's discretion if they choose not to serve them and can justify that decision. I agree that you shouldn't lose out because one idiot has one/ten too many.
Crazybroadsword, Cabin Crew do NOT get a cabin door to protect them, they get a curtain at the very most. However, assuming people do their jobs right, passengers will not be 'pissed' when they board the flight in the first place, as a result the crew can remain in control of the situation. The Captain has the ultimate say in who boards that flight and, regardless of whether he has a flight deck door to protect him or not, that passenger will not be allowed to board. If it does go wrong in flight, you can't even go and talk to the passenger to try and solve it, you have to make your decision on the correct course of action by analysing the information provided to you by the cabin crew, who are sadly having to take the brunt of it behind you. It ain't as easy as you make it sound...
That's my thoughts on the matter anyway... safe drinking/flying all...
FJ2k