Etymology Dictionary... Cool! - I eat this stuff up. Ed sent me this link to an Online Etymology Dictionary.

Here's some history on the word "hacker":

hack (2) - originally, "person hired to do routine work," short for hackney, probably from Hackney (Middlesex), from O.E. Hacan ieg "Haca's Isle" (or possibly "Hook Island"). Now well within London, it was once pastoral. Apparently nags were raised on the pastureland there in early medieval times and taken to Smithfield horse market. Extended sense of "horse for hire" led naturally to "broken-down nag," and also "drudge" (1546). Special sense of "one who writes anything for hire" led to hackneyed "trite" (1749); hack writer is first recorded 1826, though hackney writer is at least 50 years earlier. Sense of "carriage for hire" first recorded 1664, which led to modern slang for "taxicab" (1704). Hacker "one who gains unauthorized access to computer records" is 1983, from slightly earlier tech slang sense of "one who works like a hack at writing and experimenting with software, one who enjoys computer programing for its own sake," 1976, reputedly coined at Massachusetts Institute of Technology.