I did a whole Hub on this subject! For me it's all a load of hype aimed at making a lot of people very rich - (hopefully my Hub will make me rich too!).
A lot of 2012 is down to interpretation. Most people assume that when the Mayan Calendar ends on December 21, 2012 it signifies the end of the world, however others interpret this as the End of an Era or Age, which is a totally different thing.
Most religions point to a major change or an End of Days, but none of them specify a date.
There's too much disinformation relating to the whole 2012 prophecies and interestingly enough Nasa has a dedicated website debunking the whole thing!
At the end of the day, if the world ends on December 21, 2012, then there's not a whole lot we can do about it - if it doesn't then ooppps there's a lot of egg on a lot of people's faces.