Some scholars believe that the Mesoamerican Long Count was designed to try and pull the Incans off sides, but that is a minority view.
NASA has a whole page devoted to explaining why the world will not end on 12-21-12. But, NASA has a vested interest in keeping the world going, if only to see how far the Voyagers I & II can go and keep sending back signals.
I don't really think the world is going to end on the 21st. But just in case, the question I Tweeted yesterday was:
Does the world end at 12:01 AM or 11:59 PM on December 21. I need to know because I have a lunch scheduled and I'm not sure whether to cancel it.
Happy Mesoamerican Long Count.
Also a Mullfoto of a very cute infant's tee shirt from NPR.