WSJ says maybe it wasn’t Russian hackers, as one theory has it, but rather a result of Freedom of Information requests. Someone inside East Anglia found the docs and deliberately released them into the wild.
The documents show EAU scientists were trying to spin the data their way, which while this might be human, is also utterly foreign to the scientific method. They certainly have managed to screw things up for the rest of us.
They base their conclusion that it was an inside job on a detailed analysis, Comprehensive network analysis shows Climategate likely to be a leak, by WattsUpWithThat, which I find quite credible.