I think that the beginning of a new period in the Long Count of the Maya in 2012 is just as unimportant as the 6000th anniversary of the Biblical creation date (celebrated in 1996), or the planetary conjunction of May 2000, or all kinds of past dates for which the end of the world had been predicted. Someone who did not hear about the prediction in advance would not have noticed anything special on those dates, and I predict that December 2012 will be like that as well.
The only effects that can be expected associated with the conjunction of 21 December 2012 have to do with the attention that people draw to that conjunction and date. If people expect that unusual things will happen on a certain date, then on that date they'll behave differently than usual, and that in itself is already an unusual thing. In this way they can fulfill their own expectations.
If you researched this topic enough, you'd know that well many predictions of the end of the world have come, and gone. Guess what its still here
/me goes out and smells the air
yup its still here.
http://www.astro.uu.nl/~strous/AA/en/2012.html