I don't believe in it.
1: Nostradamus his predictions are very unstable. I recently saw a program about him. They did some tests and it appeared that people just saw in the predictions what they wanted to see, depending on the situation. His predictions could be interpretated in a lot of ways. In most of his predictions he uses pretty common words, or he formulated in such a way that it's impossible to actually understand what he said.
That was his strength, he wasn't making real predictions, he was just formulating common things that occur a lot, but did it so that it could be adapted to anything.
I can't remember that his book just got discovered recently, because this is pretty old.
2: How could the Maya's predict that far ahead. Honestly said it's stupid, people these days are very sceptical, but they do believe that some civilization from 1000 years ago can predict the future >.<
Also it's possible they interpretated it wrong. After the translation it seemed that their calender stopped in our year 2012, however they don't mentioned anything about the destruction of the world. It's very possible that it's just a cycle, that after the year 2012 a new cycle starts (one of 2560 years or something), just like spring or a normal year.
And I need to say that recently there have been made some evidence that the translation had some mistakes and that it would some centuries later than 2012,