There is only one "exit permit" point -- Trail Crest, and then only if you pass through Trail Crest coming up from the west side in order to return to the Portal via the Main Whitney Trail.
The Whitney Zone, on the other hand, merely means a $15 (versus $5 elsewhere) permit reservation fee, when reserving permits in advance.
On a permit-related issue, I just noticed that there is now a daily quota during the quota season for the North Fork of Lone Pine Creek (MR) this year -- 10 per day, of which 6 are reservable, and 4 are not. I guess this was bound to happen sooner or later....