Dead with a broken neck that's what.
Oh should I have included spoilers? No. Why? Screw you that's why.
One of the things about Man of Steel that seems to be bugging a lot of people is Superman killing General Dru-Zod at the very end. The main reason is that Hollywood has led to the perception that Superman, like all other superheroes does not kill. This is reinforced by Alan Moore's Superman doesn't kill line in his famous work Whatever Happened to the Man of Tomorrow? and Mark Waid's recent sentiments. Everybody is subject to their own opinions but the truth is that nobody can interpret a character fully without looking at all the evidence first.
The first thing I want to do is say for a fact that Superman has made a history of killing Zod. As I'll list his comicbookkills, I'll just give the first one here: De-powers Zod and throws him in a pit of doom. That is Superman II for you.
Now on to the comic kills:
Whatever Happened to the Man of Tomorrow: This is an honourary mention. It doesn't count, especially because of how Superman killed Mxy, the dam imp essentially killed himself. Reinforcing this as a mention, Superman depowers himself stating that he didn't have the right to take five dimensional life.
John Byrne's Run: Here is the second Zod kill. Superman meets an alternate universe Zod, depowers him (there's a history to this method, a dangerous method) and then kills him. Why? Zod threatens to regain his powers and kill everybody in Superman's world. This story is no longer "canon", but that is what we make of it. But still, this story showed that he's not a killer, but he has killed. What is the significance of this death? That Superman killed a Kryptonian, affirming that despite his heritage, he would do anything to protect humanity.
Doomsday: The most famous example of Superman killing was this moment. No, neither stayed dead and yes, Doomsday "evolved beyond death". I do believe in evolution but that was just stupid. Doomsday would not stop his onslaught and Superman had to decide, either not kill and let Doomsday thrive or kill the unstoppable force. He did just that, and like the comic era of the 90s, it didn't last. Significance of this death? Superman will do the unthinkable only if he needs to.
Superman/Batman: Basically an evil Superman from an alternate future comes and Superman shoots him with a Kryptonite bullet, getting him crushed by a car. Some people could argue that it was the car that killed him, but come on. The significance of this death? Only Superman can stop Superman, and the only way to stop Superman is to kill Superman. Did I say Superman too many times there?
There that's three official with one unofficial. Now lets go to the Man of Steel death. The point of that death was that Superman had to choose between making himself the Last Kryptonian (whose not in prison) and saving humanity. Maybe he could put his hand in front of Zod's lasers, but that would be plain stupid. What happened was the right thing, Superman saying I will not let you kill an innocent family. That was Superman being pushed to his limit and being forced to do the right thing. That was Superman doing what he needed to do to show that his adopted world was what meant most to him.
Some time around Thursday to Sunday I'll have my Man of Steel review up.