The U.S. Copyright Office and the Library of Congress have recently announced several new exemptions to the Digital Milinimum Copyright Act, a 1998 law that prohibits people from bypassing technical measures that companies put on their products as copyright protection.
The rules apply to all forms of electronic devices, but will be enjoyed mostly by owners of Apple's iPhone. Until now, iPhone users have described themselves as being "in jail" since they could only install software and applications pre-approved by Apple and downloaded only from Apple's iTunes store. Unlocking the phones is known as "jailbreaking" and had, up until this decision, been illegal. With this new rule in place, software developers can create, market and sell their own iPhone software without having to obtain permission or approval from Apple. In addition, those with the technical expertise will be able to use the unlocked iPhone with any cellular provider.
While "jailbreaking" is now technically legal, that doesn't mean Apple won't do everything in it's power to stop it. So if you do jailbreak your phone, keep in mind that you will probably void your Apple warranty and be forbidden from downloading software updates.
Final note: The new exemptions also allow bypassing of copy-protection and security encryption software placed on DVD or Blu-Ray discs if there is a legitimate fair use purpose.