Guys, it's simple and it's really not that frightening. I personally was getting curious about the 2012 stuff for a while, but it just aint that mysterious.

Every 2250 years (or so) we go through an "Aeon", one of 12 Aeons that make up something like 24,000 years that envelope an astological cycle that takes that long to complete. This is why many cultures all point to 2012, because it's the end of this Aeon. So quite simply, it's nothing but the alignment of stars and the mythology attached to those stars.

The Mayans were able to accurately predict many things *gasp* because those predictions involved celestial events like eclipses and star alignments. Any civilization that developes a good understanding of patterns of movement in the heavens can work it down to a science with astronomy and mathematics, and thus predict events. How the Mayans managed to work out such a complex science, one we've only recently mastered ourselves, is mysterious and impressive enough in and of itself. But these predictions, nontheless, are possible with a solid foundation in the sciences.

2012 will be little more than an alignment of planets and stars that only happens every so many thousand years.