Passed through IST last evening, took of just an hour before the events, only heard about it eight hours later from the immigration officer at the other end.
From what I gather the attacks were NOT in the terminal building, but in the adjacent parking building (which is connected to the terminal on both levels). Absolutely agree with Rex above, in this case security arrangements worked as planned, they never got inside the terminal. This could have happened at any other crowded place in Istambul (as it did, several times...), or at any other major city. The only effective defence is intelligence, to pick out the rotten ones before they do anything, but yes that does involve tracking communications.