I have to agree with Ogre. Still sock up on Ammo.
I highly doubt 'the end of the world' comes. I think it's gonna be more of a 'new beginning' in the terms of Humanity. Which is like starting a new chapter of a new book instead of the SAME old book we've been living through the last 5k years of life on this planet. We as a people are going to have to figure out a way to survive with our technology and NOT let our technology be the death of us.
Mankind's demise, if it's going to happen, is going to be of our own making. We know that, we all know that. If the ''End of the World'' happens it will be of our own creation, not of God's(I am a devout Christian btw), or a solar event. Tho a Solar Flare is the most likely thing to happen that could effect the ENTIRE PLANET and knock all 7 Billion of us back to the 19th Century, send the world into Utter Chaos, where the weak will die off and the strong who stick together will survive.
And I highly doubt Iran obtaining even 2-3 nukes is enough to cause any 'End of the World' scenarios. The U.K. and the rest of Europe, who have taken a more silent stance compared to us in the U.S. and our buddies in Israel, WILL NOT allow Iran to gain a foothold by holding the Middle East hostage with Nukes. It's too close to their homes. If it comes to it you will see France and England the first ones in the door over there in Iran. I have faith in our buddies in Europe. They know the cost of standing by Idly. The last 2 World Wars were hosted by them and with the backing of the World's super power, the United States, we'd never allow it to become so critical.
So before you get too hopeful of being able to blow the head off your annoying neighbor (Who refused to listen and buy a Glock LOL) after he is bit by a Zombie, I'd focus more on our own creations that have the ability of wiping mankind out.
But still, don't think of 12-21-12 or w/e it is as the end of the world. Think of it as a NEW BEGINNING we are so very lucky we get to be part of. Nowhere in the past has mankind been so close together, so technologically able, to a point where the FUTURE IS SO UNCERTAIN. We are lucky to live in these times. We are lucky to be able to bear witness to the end of an Industrial Age and welcoming in the Technological Age. More luckier than the times of our Father's and Grandfather's. I say, whatever happens happens, if **** hits the fan, I'll be on the front lines to welcome it. Whatever it may be, a War, or utter Chaos. I'll not miss my chance to be involved and many of you here won't either.
Even tho I wouldn't mind chopping or blowing the head off a few Zombies.

Especially a few people I know.