As promised, Dan Rosenberg aka djrbliss on the XDA Developers forum released some additional details about his attempts to unlock the Samsung Galaxy S 4. Yesterday he posted a pic showing the unlocked bootloader that seemed to indicate he had recovery capabilities. He confirmed that in his latest post on the subject where he reports his work will allow custom kernels and recoveries.
Rosenberg also confirmed he had achieved the unlocking on an AT&T variant of the Galaxy S 4. However, he is not planning to release any details until Verizon starts to ship their version later this month. If you think you will be interested in unlocking your new Galaxy S 4 using Rosenberg’s tools, he does recommend that you not accept any OTA updates prior to his publishing his release despite the risk of missing out on security updates.
source: XDA Developers forum