There's been some talk recently of potentially delaying the Presidential elections if there is a terrorist attack soon before them; some of this talk has been interesting, although most (as is often the case when political partisanship enters the discussion) is a bit childish.
My thought on the matter is this. The elections should not be delayed. The only reason for delay would be fear of excessive foreign influence on the election process. The Electoral College was set up by the Founding Fathers in part in order to shield the Presidential elections from such influence. A terrorist attack would put the Electoral College to the test as it has never been put to the test before; but it is there for precisely this sort of reason. And so long as the states have their election laws in order, it will work.
-> As it turns out, I'm not the only one to think so; see this op-ed at the Washington Times.