Some say that it will find the God particle.
Others say that it will kill us all.
I say hope for the best, but [http://instructables.com/community/Its-the-End-of-the-World-As-We-Know-It-.../ prepare for the worst.]
For more information, look at these newer posts:
More on the LHC Countdown
and End of World One Step Closer. Or Not.