I only heard about this earlier this year. There was a whole show on either the History Channel or Discovery or something. It said that there were other groups that pointed to 2012, too, not just the Mayans. It was kind of creepy but way interesting. It's all based on the "galactic alignment" where the winter solstice sun and the galactic equator line up.
I think it's just another example of people freaking out over an astronomical event.