The Mayan calender ended in 2012. That does not say that the world will end in 2012 does it?
It could mean that the world as we know it will end, bringing with it a new era of some sort.
I've said this before and I'm going to say it again; there have been numerous "doomsday" dates predicted, yet we're still here to tell the tale.
Seriously, I wouldn't waste time in worrying about this whole 2012 thing.