Okay, all very impressive, but didn't someone mention a black hole?

Well yes, one possible result is that the LHC will produce microscopic black holes the size of atoms. This, contrary to popular speculation, would be great. In fact, some theories predict that we should produce them. However, rather than sucking in the world, these would decay in the detector - exploding in a spectacular shower of subatomic particle that would light up the detector like a Christmas tree. I've seen experimental plots of an event like this. People take it very seriously and would be very excitied if it happened.

But, I hear you shout, what if it doesn't decay? What if the black hole sits there, getting larger and larger until it ate the world?

Well, this has been carefully studied. Though we have never created collisions at this energy in a laboratory on earth before, these type of interactions do occur when cosmic rays hit the earth from outer space. So if this was going to happen, it would have done so already. Okay, so maybe we're just lucky that this hasn't happened to us yet? No. It hasn't happened to us, or to Mars, or to Jupiter, or the sun, or any other object we can see. This was addressed in a recent paper (out this week). I think the abstract (or at least the last line of the abstract) is worth a read:

http://arxiv.org/abs/0806.3381

So no, we will not be destroyed by black holes produced at the LHC. The same arguments (that such interactions have taken place in the earth's atmosphere for its entire lifetime and so any bad thing that can happen should have happened already) is a pretty solid argument against all 'LHC will destroy the earth/universe' theories.

On the other hand, humans are a pessimistic bunch and everyone likes to think the scientists will get it wrong, so I believe that there are a number of End of the World parties being organised for early August....