Samsung will sell a special developer edition of the Galaxy S III to customers on the Verizon network for $599 through their developer portal. This smartphone will come with an unlocked bootloader, unlike the standard phone that Verizon sells where the bootloader is locked. But before you think this is some super elite hacker phone, it's important to remember that other carriers like AT&T already offer the Galaxy S III with an unlocked bootloader.
Verizon locks the bootloader on their S III simply because they don't want users customizing the device on their network. They believe that having a user tamper with the phone would prevent them from providing an optimal customer experience and hamper their ability to provide technical support. Additionally, a hacked phone could prove difficult to connect to the Verizon network and worse, could impact the experience for other customers. It's worth mentioning that unlocking a standard phone also voids the warranty.
Customers will only be able to purchase the developer edition of the phone through developer.samsung.com as it won't be available in stores. Interesting enough, however, the phone is being sold with Verizon's approval, so it's not like you are breaking any rules to get the unlocked device.
The developer edition will ship with a standard warranty but should a user brick the phone by installing custom software, it will not be covered under warranty. No word yet on when Samsung will make the handset available for purchase.