Update:The Pangu iOS 8 - 8.1 jailbreak is stable and available for both Mac OS X and Windows in English. You can learn how to jailbreak any iPad or iPhone running iOS 8 - iOS 8.1 for Mac OS X here or Windows here.
Yes! Team Pangu released an iOS 8.0 - 8.1 jailbreak on October 22, 2014. This is the first time that a jailbreak has been released before a new Apple product was officially launched. The Pangu iOS 8.0 jailbreak was released mostly as a developer's tool that did not come bundled with Cydia. However, Cydia creator Saurik has updated the software to support iOS 8 and it is available now as a separate .deb file on his website.
Casual users are encouraged to wait until Pangu releases a complete jailbreak before jailbreaking any devices. Developers who want to download the Pangu iOS 8.0 v1.0.1 can do so now from the Pangu website. The jailbreak tool is also only compatible with Windows computers and there is currently no English translation available.
You can download the iOS 8 version of Cydia from this link.