Well, I found this on Wikipedia. Not sure how valid the information is seeing as how according to Wikipedia, Stephen Colbert is responsible for saving the African Elephant, but this is what it says.
http://en.wikipedia.org/wiki/Maya_calendar
he end of the 13th b'ak'tun is conjectured to have been of great significance to the Maya. It does not necessarily mark the end of the world, according to their beliefs, but a new beginning or time of re-birth. According to the Popol Vuh, a book compiling details of creation accounts known to the Quiché Maya of the colonial-era highlands, we are living in the fifth world. The Popol Vuh describes the first four creations that the gods failed in making and the creation of the successful fifth world where men were placed.
The last creation ended on a long count of 12.19.19.17.19. Another 12.19.19.17.19 will occur on December 20, 2012, and it has been discussed in many New Age articles and books that this will be the end of this creation, the next pole shift or something else entirely. However, the Maya abbreviated their long counts to just the last five vigesimal places. There was an infinite number of larger units that were usually not shown. When the larger units were shown (notably on a monument from Coba), the end of the last creation is expressed as 13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.0.0.0.0, where the units are obviously supposed to be 13s twenty places larger than that b'ak'tun. In this age we are only approaching 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.13.0.0.0.0, and the larger places would all need to similarly roll over to 13 again to match the date of the new creation.[6]
This is confirmed by a date from Palenque, which projects forward in time to 1.0.0.0.0.0, which will occur on October 13, 4772 (a Friday). The Classic Period Maya likely did not believe that the end of this age would occur in 2012. According to the Maya, there will be a baktun ending in 2012, a significant event being the end of a 13th 400 year period, but not the end of the world.