Apple issued a warning today to scare iPhone buyers that it's not a good idea to unlock the phone:
Apple has discovered that many of the unauthorized iPhone unlocking programs available on the Internet cause irreparable damage to the iPhone's software, which will likely result in the modified iPhone becoming permanently inoperable when a future Apple-supplied iPhone software update is installed.
Apple plans to release the next iPhone software update, containing many new features including the iTunes Wi-Fi Music Store (www.itunes.com), later this week. Apple strongly discourages users from installing unauthorized unlocking programs on their iPhones.
Users who make unauthorized modifications to the software on their iPhone violate their iPhone software license agreement and void their warranty. The permanent inability to use an iPhone due to installing unlocking software is not covered under the iPhone's warranty.