As some general info, they are doing research primarily to find the Higg's Boson, otherwise known as the "God Particle." This handy little boson is theoretically what gives matter its property of mass. It is a chargeless particle. Other bosons are what make up the weak nuclear forces. They also plan to do research on dark matter and antimatter. Cool stuff overall.
The downside is that many people were/are freaking out about it, saying that the things created could destroy the world
. The scientists working on it and the folks at CERN even got death/bomb threats about starting it up. They even had people calling them, crying and wailing, to please not start it up. That being said, they finally told all of these people that the earth gets bombarded constantly with the kind of energy (and stronger) the LHC gives off--and that hasn't created black holes, armageddons, etc. Anyway, here is the official site at CERN: http://www.cern.ch/lhc
also, http://public.web.cern.ch/public/en/LHC/LHC-en.html
Edit: forgot this. It's pretty funny--just about the geekiest rap song you could come up with: http://www.youtube.com/watch?v=j50ZssEojtM