There are about fifty threads on this topic already.
It so happens, in the current epoch, that the position of the sun in the sky at winter solstice aligns with the plane of the galaxy, in approximately the direction of the galactic centre. This happens every year, with no noticeable effect. Precession of the equinoxes moves the alignment gradually so that there is a moment of "best alignment". We don't need to wait until 2012 for it to occur, however: it happened a few years ago.

Grant Hutchison