Here's a better explaination, curtesy of wikipedia (of course!) of what the heck is actually happening/feeding all the buzz (what buzz???)
According to the Popol Vuh, a book compiling details of creation accounts known to the K'iche' Maya of the Colonial-era highlands, we are living in the fourth world. The Popol Vuh describes the first three creations that the gods failed in making and the creation of the successful fourth world where men were placed. In the Maya Long Count, the previous creation ended at the start of a 13th b'ak'tun.
The previous creation ended on a long count of 220.127.116.11.19. Another 18.104.22.168.19 will occur on December 20, 2012, followed by the start of the fourteenth b'ak'tun, 22.214.171.124.0, on December 21, 2012.
Yaaaay. This is where the end of the world idea comes into play.