Why do people think the world is ending in 2012?

I was watching Fox8 News here, a normal local station, and there was a commercial for The Institute of Human Continuity (www.theihc.com). These people are having a lottery to decide who to save from the catastrophe's that are going to cause some apocalypse in 2012, and they are electing leaders to govern the survivors. I was shocked to see this commercial on a reputable TV station. A friend of mine also told me her boyfriend keeps telling her that natural disasters are going to threaten to destroy the earth in 2012. Do people seriously believe this? What are people basing this belief on? This has made me very curious as to where this is coming from, and if another Y2K-type drama is looming in the near future. Any info on this would be appreciated.