Ok, this will be a long one, covering a couple of subjects, but here are my thoughts.
First, I heard a brief mention (may not be true) that FEMA had been activated and they were using their "weapon of mass destruction" protocol. Of particular interest with regards to freedoms, it is my understanding that that protocol calls for a suspension of the constitution and a declaration of martial law. Have to wait and see on that one.
With regards to the terrorist act itself, what was the logic of the attack? I think an act of this magnitude is the type of act that will "wake the sleeping giant". I don't think any group or government will be willing to take direct responsibility and become the focus of our rage. This puts us firmly in the camp of Israel as a fellow nation victimized by terrorists. I don't see anymore support or sympathy for Palestinians cheering at American deaths. So, where does this lead? I believe that in addition to causing death & destruction in the U.S., the goal is cement support among the Islamic terrorist groups and to foment a widespread war between all of Islam and the western nations. If they can provoke a response from us that pulls the rest of Islam (who currently don't support terrorism)into a war, they will have achieved their goal.
Finally, I think this will bring about a change in what constitutes an "act of war". Traditionally, it takes an act by a sovereign nation to legally be an "act of war". Even if we can't firmly link this to a particular nation, it must still be considered an act of war. Potentially, this will trigger the treaty obligations of our NATO partners in any military response we may make. This would be an act of war against the United States. It would also remove our response from the confines of the Justice Department. We would not seek to bring criminals to a court and the bar of justice, rather we would simply seek to kill them. I'll go along with that.
Anyway, just my thoughts.
P.S. One last thought and caution. The purpose of Terrorism is to create terror. If you limit your attacks to well know targets of strategic, financial or political value, than somebody in Podunk, Kansas can rationalize, "I'm safe if I don't go to New York, or Chicago, or Washington D.C., etc. But if the next bombing is in Topeka, or Boise, or Provo, UT, i.e. rural America, than no one will consider themselves safe anywhere. I think there is a good chance that we will see another wave of attacks as well.