Coming from a person who absolutely refuses to fly (since long before September 11) you may want to take this with a large serving of salt.
With no disrepect to Jo-Anne, I think it's best that people know what is happening, and the threats that the intelligence community become aware of. Apparently this one was corroborated by more than one source - one senior official in the Department of Homeland Defence ranked its credibility as a 6 or 7 on a scale of 10 (with 10 the most credible).
My own feeling about this style of hijacking is that it likely is not going to be as successful - I guess I should say catastrophic, as it was on September 11 for the following reasons:
1) The presence of Federal Air Marshalls.
2) Armed pilots.
3) Bullet proof, LOCKED, cabin doors.
4) Stepped up screening and security - although still fallible.
Finally, and this goes back to the "staying informed" philosophy, passengers who will no longer sit still and just "do as they are told". We all know how the cell phone was used on September 11 - when the passengers on Flight 93 found out what was taking place in New York and Washington they fought back. I believe that future terrorists will encounter the same resistance - when faced with cowardly terrorists intent on using the airframe as a weapon, passengers will resist and take control of their own destiny.
If I flew, I would take some heart in that. If I flew.
And I agree with Jo-Anne - refuse to live in fear. "Let's ROLL!!!"