Update (October 22, 2014):
Pangu team has just released a jailbreak for iOS 8 – iOS 8.1. It works with all the iOS 8 – 8.1 compatible devices:
iPhone 6, iPhone 6 Plus, iPhone 5s, iPhone 5c, iPhone 5 and iPhone 4s
iPad Air, iPad 4, iPad 3 and iPad 2
Retina iPad mini, 1st gen iPad mini
5th...