... the real question is whether Apple is allowed to brick an unlocked iPhone.
Rulemaking on Exemptions from Prohibition on Circumvention of Technological Measures that Control Access to Copyrighted Works
The Librarian of Congress, on the recommendation of the Register of Copyrights, has announced the classes of works subject to the exemption from the prohibition against circumvention of technological measures that control access to copyrighted works. Persons making noninfringing uses of the following six classes of works will not be subject to the prohibition against circumventing access controls (17 U.S.C. § 1201(a)(1)) during the next three years.
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5. Computer programs in the form of firmware that enable wireless telephone handsets to connect to a wireless telephone communication network, when circumvention is accomplished for the sole purpose of lawfully connecting to a wireless telephone communication network.
The question is not whether it's legal to unlock the iPhone, the real question is whether Apple is allowed to brick an unlocked iPhone. That's the interesting question, and since I'm not a lawyer I don't pretend to have the answer, but here are some thoughts:
On a related note, the iPhone Dev Team is promising a patch to restore unlocked iPhones back to factory fresh condition.
So, where does this leave users of unlocked iPhones and Apple? My guess is that if iPhones start getting bricked, there's going to be trouble.