I currently have iOS 8 GM installed on my iPhone 5, however there is still no sign of how to access iCloud Drive. Am I missing something or did Apple just not flip the switch yet?
iCloud Drive isn't an app. It's something that other apps can use an API to access. And there aren't any iOS 8 apps available yet. Apple does have beta versions of their iWork apps for registered devs that use iCloud Drive. They can be downloaded from the developers portal.