While, legal to do so under current US Copyright laws, Apple has escalated its efforts to prevent iDevice owners from jailbreaking their devices. Apple has a patent application, filed in 2009, but just published last week entitled "Systems and Methods for Identifying Unauthorized Users of an Electronic Device." The patent application is for a number of security measures that would automatically protect the device from "unauthorized users".
The patent application
Updated 08-22-2010 at 12:39 PM by Gen3SF
It is Legal to Jailbreak and Unlock Your Cellphone
Jailbreaking an iDevice is Fair use
The Digital Millennium Copyright Act gives the Library of Congress the