By Neil Hughes

Published: 11:40 AM EST

The U.S. government on Monday announced new rules that make it officially legal for iPhone owners to "jailbreak" their device and run unauthorized third-party applications. In addition, it is now acceptable to unlock any cell phone for use on multiple carriers.

According to The Associated Press, the government approved a handful of new exemptions to a federal law that prevents the circumvention of technical measure that prevent users from accessing and modifying copyrighted works. The report noted that every three years, the Library of Congress' Copyright Office authorizes exemptions to ensure existing law does not prevent non-infringing use of copyrighted material.

In addition, another exemption was approved that would allow all cell phone users to unlock their device for use on an unapproved carrier. Currently, Apple's iPhone is available exclusively through AT&T, but unlocking it can allow for voice calls and EDGE data speeds on rival carrier T-Mobile.

Other exemptions announced Monday allow people to break protections on video games to investigate or correct security flaws; allow college professors, film students and documentary filmmakers to break copy protection measures on DVDs to embed clips for educational purposes, criticism, commentary and noncommercial videos; and allow computer owners to bypass the need for external security devices (dongles) if the hardware no longer works and cannot be replaced.

The warranty-voiding jailbreak process allows users to run software not approved by Apple, which has no plans to allow users to install third-party applications downloaded from outside its sanctioned App Store. Hackers have created their own custom applications -- many free, and some for purchase from an alternative storefront known as Cydia.

Apple has been criticized for its strict control over the iPhone App Store, requiring that all applications be approved before they are made available for download. The company has defended this practice, stating that it keeps faulty and potentially dangerous software from being made available, as well as banning unsavory content such as pornography.

In April, Jobs cited an unsanctioned pornography store available for the Google Android platform as a reason to not support unsigned applications. "That's a place we don't want to go," Jobs said, "so we're not going to."

In addition to allowing access to legitimate third-party software, both free and paid, through services like Cydia, jailbreaking can also be used to pirate App Store software, one major reason why Apple has fought the practice.

Hackers have been hard at work on jailbreaking iOS 4 since it was released in June. Though the iPhone 3GS and iPhone 3G have been exploited, the iPhone Dev Team has continued their efforts toward both jailbreaking and unlocking the iPhone 4. With Monday's decision by the U.S. government, their efforts are now considered legal.