Ancient Mayan civilization is one that I never get tired of learning about. Despite the astonishment I feel when trying to understand their cosmic systems, I can't really buy into this idea that there is some sort of 'Doomsday' scenario that will fall exactly on a specified date.
Supposedly, the date December 21, 2012 is the end of a cosmic cycle that the Mayans called a baktun (144,000 days). I tend to think that this is just a measurement like our century & millenium, which means time will probably continue on after 2012- just like after "Y2K."
However, there is a part of me that wonders about the greater significance of these meticulously calculated astronomical cycles.
Western measure of time is disconnected from the longer, yet regular workings of the universe. Beyond the solar year of 365 days, our measures of time are basically arbitrary.
Despite our exponentially expanding knowledge base, I think ancient people like the Mayans had a much different sense of natural time and the infinite nature of the universe.