Some of the fear mongers would have us believe that it is DoomsDay, but when taken in context to the entire algorithm of the Mayan calendar, it infers a time of "renewal". What that might mean is anyone's guess.
The movie was hilarious without intending to be ( which makes it even funnier). They crammed every Disaster Movie cliche in there they possibly could, lol.
The end of the world will come when it does. No sense worrying about it now. Could you stop it if you DID know when it was? Do the best you can for others when you're alive and do the least harm you can. Every culture has had some kind of doomsday prophesy. One of them will be right. Until then, focus on what is good and right.
My Garfield calendar ended on Dec 31st, and the world didn't end (but for me it did...I love Garfield and Odie). Anyway, the Mayan civilization came to an end so it goes without saying that they quit writing their calendar. They had to. There had to be an ending somewhere. It doesn't mean anything, they just quit writing. Or ran out of time, depending how you want to look at it.
Besides, the Mayan civilization came to an end before their calendar did. Their calendar wasn't very good, was it?