The majority on this thread seem to leaning towards the idea of passengers taking violent action in a hijacking situation after the events of September 11th.
I've checked out a couple of the pilot's boards on this subject.... They have a very different perspective and are concerned that they’ll be faced with a spate of mini-Bruce Willis’s rushing the cockpit door any time anything suspicious occurs.
The majority of hijackings still end without suicide and the last thing pilot’s want is passengers taking independent action when things are actually under (relative) control. In any type of hostage situation (e.g. deranged individual with explosives strapped to the chest in a shopping mall) the police always recommend the hostage acts calms, tries to talk to the hostage-taker and above all else does not "try anything" unless a clear opportunity exists to escape.
Of course every situation is different and there may be times where it is obvious that passengers taking action may be the only thing to do but I can’t help feeling this type of talk is dangerous.