Fact: The rumor states that the apocalypse will occur in December 2012.
Fiction: The world will end in 2012.
Meaning: The world will not end in 2012.
Reason: There is a black hole in the center of the Milky Way, and the Earth will perfectly align itself between the Sun and the black hole. This site explains why that alignment will not end the world. Basically, the gravity change from the alignment is too small to be dangerous.