I personally think this is a good move by the Governor of New Mexico. I know this guy existed and these crimes happened back in the late 19th century, but I agree on the part of "rewriting history" by giving a pardon.
Here is a Wikipedia link on the history of Billy The Kid if you are interested. Otherwise, the story on not granting the pardon is below.
Via Yahoo!/AP: The rehabilitation of Billy the Kid lies dead in the dust.
In one of his last official acts — or non-acts — before leaving office, New Mexico's governor refused to pardon the Old West outlaw Friday for one of the many murders he committed before he was gunned down in 1881.
Gov. Bill Richardson cited ambiguity surrounding the pledge of a pardon 130 years ago as the reason.
"I felt I could not rewrite history," Richardson told The Associated Press, hours after announcing his decision on ABC's "Good Morning America" on his last day in office.
Read the full thing here