The firmware is currently available via Software Update and should hit the developer website soon.
The release is a 237MB delta update for the iPhone 5.
Apple has released the new build number 11A4400f on the iOS Dev Center. It is now available for the following devices:
● iPad (4th generation Model A1458)
● iPad (4th generation Model A1459)
● iPad (4th generation Model A1460)
● iPad mini (Model A1432)
● iPad mini (Model A1454)
● iPad mini (Model A1455)
● iPad Wi-Fi (3rd generation)
● iPad Wi-Fi + Cellular (model for ATT)
● iPad Wi-Fi + Cellular (model for Verizon)
● iPad 2 Wi-Fi (Rev A)
● iPad 2 Wi-Fi
● iPad 2 Wi-Fi + 3G (GSM)
● iPad 2 Wi-Fi + 3G (CDMA)
● iPhone 5 (Model A1428)
● iPhone 5 (Model A1429)
● iPhone 4S
● iPhone 4 (GSM Rev A)
● iPhone 4 (GSM)
● iPhone 4 (CDMA)
● iPod touch (5th generation)
Please follow iClarified on Twitter, Facebook, Google+, or RSS for more information as it becomes available.