Apple filed an objection but the US Copyright Office appears to have ignored it and sanctions iPhone jailbreaking

IPhone users can now legally hack their phones to download applications that aren’t in Apple’s App Store.

The U.S. Copyright Office, a division of the Library of Congress, has authorized several new exemptions to the Digital Millennium Copyright Act (DMCA), one of which will allow mobile phone users to “jailbreak” — or hack into — their devices to use apps not authorized by the phone’s manufacturer. The new rules will be published on Tuesday in the Federal Register.

Their position is not just for applications; they continued to uphold the right to hack the phone to subscribe to another network

The Copyright Office also renewed and expanded its 2006 decision allowing mobile phone users to jailbreak their phones in order to switch carriers. Previously, the office allowed firmware updates to enable network-switching; this week, it added a provision allowing software hacks as well. In other words, iPhone users can now legally download software that will enable their phones to join a non-AT&T network.