All of the planets have been predicted to be perfectly aligned in 2012, although NASA and many astronomers have claimed that this will NOT happen in 2012. The closest will be 6 planets aligning on June 13th this year, three on each side of the sun.
December 21st 2012 is the date of Armageddon if you are to believe the Mayans so you dont have THAT long to wait that long to find out.
However, there have been many predictions that the world will end, Nostradamus was one of the most famous to get it wrong.
The world was predicted by many to end in 2000, Planet X was supposed to collide with the Earth in 2003 etc etc.
Personally, considering the Mayans were unable to survive, or predict their own demise, maybe they are wrong about the end of the world. But there could well be something in it, they were particularly advanced.
One thing we can be pretty sure of is that the Earth will survive, even if we humans do not.