I don't think the world will end. I am however eager to see what happens in 2012. The Mayans predicted that 12/23/2012 is the date that our Solar System aligns itself with the galactic center and "passes through the mouth of the dragon"!

The world has been in existence for billions of years, and will continue to exist for billions of more years. However, like every planet (or star) it will eventually implode into a black hole, but we will not be there anymore when it happen.

So, what will happen to humans when our planet implode? They will be in other planets. Science will take care of that.

Here's some rational information on the subject:

http://www.2012explained.com
http://www.dailycommonsense.com/?p=13