Due to a ruling by the Librarian of Congress, come tomorrow it will be illegal to unlock a new, on-contract iPhone -- or any phone -- in the U.S. If you bought your iPhone before tomorrow, or if you bought a factory unlocked iPhone straight from Apple, or off-contract, full priced iPhone from carriers, or your contract is over, you shouldn't be subject to any restrictions. Doing it on your own via Jailbreak, however, will be strictly verboten, and likely subject to prosecution by law enforcement and the Batman. Michael Gowen of TechNewsDaily reports:

In October 2012, the Librarian of Congress, who determines exemptions to a strict anti-hacking law called the Digital Millennium Copyright Act (DMCA), decided that unlocking mobile phones would no longer be allowed. But the librarian provided a 90-day window during which people could still buy a phone and unlock it. That window closes on January 26.

No doubt oligopoly networks built on public airwaves appreciate your understanding. Know your laws, your rights, and make your purchasing decisions accordingly.