For the Egyptians apparently their main corridor in their largest(?) pyramid is 2012 inches (they measured in inches?) long before the the main chambers open up and are sorta layered above each other in an apparent symbol of various levels of enlightenment.
The Mayans had a calendar. IT went to 2012. Maybe they ran out of space.
The Christians have the dawn of the third millennia. One day in heaven is equivalent to one thousand years on earth. ie: the second coming of Christ as symbolized by Easter. Dawn in most places is around 6am. 6am is about one quarter through the day. One quarter through the day is 250 years into a thousand years. So, IMO, if we're gonna get all symbolic this stuff can happen as far out as 2250ad.
There are other things like natural disasters, wars, and the fight for democracy throughout the middle east being seen as people becoming enlightened on some level. Right up till the end of 2012 people are gonna get stupid on this stuff. So if we're gonna take shots at people of faith ... a-fkn-gain ... please don't lump them all in the same basket because quite fkn obviously everyone believes something different.