When the Umar Abdulmutallab incident happened, I was among those (Sanchez, Greenwald, Ackerman) pointing out that "we need to consider that part of the problem is the sheer volume of information being gathered almost indiscriminately, making it difficult to divine real threats from false ones." The broad conclusion of Dana Priest and William Arkin's first article in a series on the sprawling American national-security complex is that having a hybrid public/private "Top Secret America" about the size of Detroit drinking from the fire hose means that it's "impossible to determine" whether what the government is doing is actually making us any safer.
I don't have much to say at the moment, but my immediate reaction is that the immediate aftermath of this series may lead to some changes, but my concern is that bureaucracy has incredible inertia. That's without the very strong bipartisan political incentives to avoid trimming national-security spending, lest the other side point to the end of one particular program or another as the reason an attack went undetected. If another large attack should occur, the response will inevitably be a larger bureaucracy, if only because that at least makes it look like government is doing something.