I talked on the phone today with the GSMNP public affairs office about 2013 thru hiking. They have not worked out the details on how it will work. For thru-hikers it will cost 20 dollars for your back country permit. Thats the one that was free and available at the Fontana dam box as well as all park visitors centers and the outfitter in Hot Springs for SOBO's. They have not worked out just how you will be paying the 20 bucks or if the permit will be date specific. They did go on to say that thru-hikers will be allowed to stay in any AT shelter or campground without reservations just like it is now.