Some people on this thread clearly have major neuroses with other passengers hand baggage. If I board last, and there is no more overhead space, then that is just tough.
If I pay for a business ticket which cost more and gives me more luggage allowance, I see no reason not to use it. As regards this whole debate, the bottom line is that BAA want to use any trick to maximise profits, including tight restrictions on hand luggage, and blaming the paying passengers for any delays (due to understaffing). Never forget, that EVERY time you go through security at an airport, you are paying to do so. It is not a free service.
I cannot think of many other service industries where such poor service is offered, with no recourse for a refund, or alternative supplier. It truly is a gravy train for BAA, there is no alternative, and passengers seem happy to accept that all of it is their own fault for being slow or stupid. So tell me why BAA should give a flying f***? They are maximising their profits, that's all, and the media/public seem to believe any old guff they issue in press releases.
Soon a new rule will be introduced: you cannot take any hand luggage at all through security (in order to speed things up, of course), but you are allowed to purchase up to 7Kg in weight of duty free goods (at high street prices or more!) from BAA concessions. A nice little earner!