The Pangu jailbreak tool for iOS 8 has only been available for Windows users since the initial release
of the jailbreak. Mac users have been forced to either run Bootcamp, or some kind of virtual machine software to run Windows independently and jailbreak their devices that way. Fortunately, this won't be the case forever.
Pangu promised that they would begin work on a Mac OS X version of the Pangu jailbreak tool