Many things have been told today about security. The best quote I have comes from Bruce Schneier's blog:
We need to resist the urge to react against the particulars of this particular terrorist plot, and to keep focused on the terrorists' goals. Spending billions to defend our trains and busses at the expense of other counterterrorist measures makes no sense. Terrorists are out to cause terror, and they don't care if they bomb trains, busses, shopping malls, theaters, stadiums, schools, markets, restaurants, discos, or any other collection of 100 people in a small space. There are simply too many targets to defend, and we need to think smarter than protecting the particular targets the terrorists attacked last week.
Smart counterterrorism focuses on the terrorists and their funding -- stopping plots regardless of their targets -- and emergency response that limits their damage.
Simple thing, we know about it, but still, somehow, it doesn't work. We concentrate on things that don't help: id cards etc. Probably that's easier...