For a historic account of US phreaking (not Mitnick-specific), check out the book "Exploding the Phone: The Untold Story of the Teenagers and Outlaws who Hacked Ma Bell". Its worth as much as its long title. It even contains a historic account of the US (and international) phone system and how the monopolies came around. I read it because it was all just before my time (I'm mid 30s now). People who were blind phreaking by whistling. Insane!

(Mitnick-specific I can also recommend the docu Freedom Downtime and the book Ghost in the Wires but I've seen both already covered in other posts.)