They are emails to and from former Arizona Senate President Russell Pearce (R) and they make a good case that the "show Me Your Papers" law SB 1070 was motivated by racial hatred. These emails were obtained as part of potential evidence to prove to a federal judge that the law should not go into effect.
A few choice quotes:
“Last week, Denver’s illegal aliens sang our national anthem in Spanish and bastardized the words of OUR country’s most sacred song.”
"Corruption is the mechanism by which Mexico operates. Its people spawn more corruption wherever they go because it is their only known way of life.”
“We are much like the Titanic as we inbreed millions of Mexico’s poor, the world’s poor and we watch our country sink.”
More here at Think Progress if you can stomach it.