Android 6.0.1 Marshmallow in now available for Samsung Galaxy S6 (and the Edge version) in South Korea.
This closes a brief beta testing for limited number of users.
The final version brings some minor UI changes (updated notification menu, power menu) along with changes such as enabling the fingerprint sensor to work with the software other than Samsung's.
The update is on its way out of South Korea, but the date is not known yet.