Short answer from NASA: No. The world will not end in 2012. At least, not according to the reasons found in the film 2012.

The detailed answer is here: NASA – 2012: Beginning of the End or Why the World Won’t End?

As an aside, I came across this because of a comment from someone who thought this was sad: that NASA had to debunk the movie. But to me, I think it is a great idea that NASA did this. If films like 2012 encourage people to learn more about science and be more science-literate, then that is a good thing. In fact, in answering these questions, they touch on astronomy, geophysics, and science history. Perhaps some kid reading this will be interested in learning more about these things. I remember watching “Chariots of the Gods” when I was a kid, and I was determined to know more about these things. Dubious science fiction can lead to better knowledge.