iPhoneSIMFree's software solution to unlock the iPhone is now officially available from resellers throughout the world. The software has been tested and confirmed by multiple sources and both Engadget and Gizmodo have articles with video detailing the process of unlocking an iPhone using iPhoneSIMFree.
Reportedly, the unlock process will survive a restore of the iPhone and all iPhone features with the exception of visual voicemail (which requires back-end support form AT&T) function normally. This doesn't guarnatee that future updates from Apple won't circumnavigate iPhoneSIMFree and re-lock the phone.
For those in countries where there is no anticipated iPhone availability in the immediate future, spending $100 to unlock the device may not seem so pricey, even if there is a possibility of Apple one-upping iPhoneSIMFree and re-locking the phone at some point in the future. For US consumers, however, it may seem a less tempting expenditure given that for slightly more money you can terminate a contract (or wait for one to expire) with another carrier and switch to AT&T and not have to worry about future updates disabling your iPhone.