The New IOS 8 has been released by Apple. All who want to download/install new iOS 8 with new features can make it from here. But... Don't forget, if you want downgrade iOS 8 to iOS 7.1.2 for all iOS 8 confirmed idevices here. How?
Yu can see this complete guide from us:
Step 1: Turn the device off, connect it to the computer via USB, and launch your last version iTunes
Step 2: Place the iOS 8 device into DFU mode: with the device off, hold down the Power and Home buttons together for 10 seconds then release the power button, continue holding Home button until iTunes notifies you of a device in recovery mode being detected. The devices screen should stay black as if turned off.
Step 3: Restore within iTunes through either method a or b:
a) Restore from the iOS 7.1.2 backup you made prior to installing iOS 8 beta
b) Restore to iOS 7.1.2 IPSW by Option-Clicking the “Restore” button, and then restore from iCloud backup when finished
Step 4: Let iTunes restore back to iOS 7.1.2, the device will reboot when finished.
source : site&forums
Step 1: Turn the device off, connect it to the computer via USB, and launch your last version iTunes
Step 2: Place the iOS 8 device into DFU mode: with the device off, hold down the Power and Home buttons together for 10 seconds then release the power button, continue holding Home button until iTunes notifies you of a device in recovery mode being detected. The devices screen should stay black as if turned off.
Step 3: Restore within iTunes through either method a or b:
a) Restore from the iOS 7.1.2 backup you made prior to installing iOS 8 beta
b) Restore to iOS 7.1.2 IPSW by Option-Clicking the “Restore” button, and then restore from iCloud backup when finished
Step 4: Let iTunes restore back to iOS 7.1.2, the device will reboot when finished.
source : site&forums