In its third review of permissible DMCA (Digital Millennium Copyright Act) exemptions, U.S. Congress has lifted the ban of unlocking cell phones so they can be used in rival networks. The exemptions in general "allow people to circumvent the copyright protections surrounding digital content in particular circumstances."

This year 6 new exemptions were introduced. "Other exemptions allow media studies and film professors to circumvent access controls to make compilations for educational purposes, allow librarians and archivists to remove security measures to preserve copies of obsolete programs and games, and allow users to bypass a program's requirement for a special dongle if a replacement for the hardware is not readily available. The last case allows accessibility programs to disable the security of e-books if all version have access controls that prevent a read-aloud function." (source)

Multiple news stories available through Google News. You can also check all the new 6 exemptions here. The exemptions will take effect on Monday Nov 27th and will last for three years.