You can now use words like "bomb" at the airport. You'll get a warning instead of being arrested.
But I think it has to be in certain context. "That concert last night was the bomb!" or "That movie really bombed." will get you a warning. "I have a bomb and I'm gonna blow everyone to kingdom-come!" will get you arrested. In the old days, all three would have gotten you arrested.
(To my international readers, this applies to Canada. It's probably not the same elsewhere.)
These rules still beg the question "How many acts of terrorism have been prevented by these laws?" I figure if someone is intent on getting a bomb on a plane, they're probably not going to mention it, regardless of the rules. You wouldn't want anyone to know your intentions.
On the other hand, if you were the unwilling participant you might want to be arrested. But, even without the law, you could mention it, get arrested (for having the bomb, not mentioning it).
But, on the plus side, I'm no longer afraid of seeing my friend, Jack, on a plane and yelling "Hi!" to him.