The Pangu Jailbreak for iOS 8 has arrived with English support and full Cydia integration. Much like the original Pangu, the tool makes jailbreaking an iOS device incredibly simple. All devices officially supported with iOS 8.0 - 8.1.x can be jailbroken using Pangu. For Windows instructions see below.
Here is a complete tutorial explaining how to jailbreak iOS 8 with Pangu on Windows. To begin, make sure the iOS device is indeed updated to iOS 8.0 or later. In order to prevent problems, it is recommended to update from iOS 7 using the latest version of iTunes on a computer. Those with previously jailbroken devices should backup, then restore to iOS 8 to get started. Follow these steps to use the Pangu Jailbreak:
1. Backup your iOS 8 device with iTunes, iCloud, or both.
2. Turn off the Passcode under Settings -> Passcode -> Turn Passcode Off.
3. Turn off Find My iPhone in Settings -> iCloud -> Find My iPhone.
4. Download the Pangu Jailbreak tool from http://en.pangu.io/ to Windows.
5. Right-click on the Pangu software icon and choose Run as administrator.
6. Click Yes if prompted by User Account Control.
7. Connect the iOS 8 device to the Windows computer.
8. Unlock the iOS device and tap Trust when the dialog appears.
9. Click the Start Jailbreak button.
10. Switch the iOS device into Airplane Mode under Settings -> Airplane Mode.
11. Click the Already did button.
12. Do not disconnect while Pangu jailbreaks the iOS 8 device!
13. When complete, the iOS device will reboot.
14. Tap the Cydia icon on the home screen to launch the jailbreak app store.
15. Cydia will configure the filesystem.
16. Reopen Cydia when complete, and tap Changes -> Update to install available updates.
That's it! The iOS 8.x device is now jailbroken. Stay tuned to the iPhoneFAQ Twitter feed for news and the latest jailbreak tweaks. Developers are working to update their software to customize and expand iOS 8.