Today is a great day to be a physicist, the Higgs boson particle has been officially discovered at 4.9 sigma standard deviation (which means they're 99.9999% sure). The director of CERN said "As a layman I would say: I think we have it."
For those that do not know, the Higgs boson is the particle responsible for all other particles having mass.
There're some nice articles here if you didn't manage to catch the livestream, the first (from the BBC) is much more summarised whereas the second is a written account of all the proceedings. I'd say they're worth reading, but I'm slightly biased. BBC News - Higgs boson-like particle discovery claimed at LHC Higgs boson announcement live: Cern scientists discover subatomic particle | Science | guardian.co.uk