Is pretty much the same lesson we didn't learn from the Fort Hood shooter, or for that matter, the 9-11 conspirators. That lesson is that the enemies of this country are serious about doing us harm. We are not serious about defending ourselves.
The knicker-bomber bought a one-way ticket with cash. Further, his father had warned authorities that his son was a threat. He was even on the watch list. How many friggin red flags do they need? But wait--it's better to let a plane filled with innocent passengers go down in flames than be accused of profiling.
Have you ever noticed that no one ever hijacks an El Al airliner? Do you wonder why that is? Maybe someone ought to check into it....
On a side note, I wonder how that whole, "49 virgins," thing is going to work out now that the boy has blown his nads off?