This is actually rather exciting. If micro-black holes are generated after the high-energy collisions inside the LHC, they could provide the first experimental evidence of Hawking Radiation, the only radiation predicted to be emitted from a black hole's event horizon. If the radiation predicted by Stephen Hawking is discovered (via the detection of evaporating black holes), a Nobel Prize for Physics wouldn't be far away.
Hold on, isn't there a mixed message here? On the one hand, we have conspiracy nuts scaring the world (yet thrilling the tabloid press), saying that "reckless" physicists could destroy the world with a black hole, and then we have physicists confirming that they would love to see black holes generated in the LHC. What's going on?
It's a little thing called mass, and the micro-black holes that are theorized to be produced by the LHC simply do not have enough of it to cause any damage.
More Mass = More Suck
Cosmic black holes are created after the collapse of a massive star. They are, by definition, massive. If something is massive, it has a strong gravitational field. Any planets, stars or space cows that stray too close will be sucked in, making the black hole more massive.