A teen hacker known for his deftness with iPhones has figured out how to unlock models running the latest firmware versions by cracking a protection that that has frustrated hackers for weeks.

The breakthrough by George Hotz, aka Geohot, means people who have bought a recent iPhone will once again be able to use it on the phone network of their choice. Apple makes as much as $400 for every handset that's activated on an approved network, so its developers have worked hard to prevent the so-called unlocking of iPhones.

Last year, 17-year-old Geohot was among the first group of hackers to break Apple's iron-fisted grasp on the iPhone, a coup that won him a Nissan 350Z and 3 8GB iPhones. Apple promptly responded by issuing updated firmware that stymied such efforts. Not only did the updates disable modified phones, effectively turning them into $400 bricks, they also prevented unlocking software from working in many cases. The arms race has persisted ever since.

The latest salvo was fired late last week, following a 24-hour hacking spree by Geohot that was broken up by only three hours of sleep. It turns out the latest firmware contained modifications to the device's memory registers to prevent unlocking. Geohot worked around those changes by finding another, much higher register that was vulnerable.