1 & 2 - Superman: The Movie (2-Disc Special Edition)
3 & 4 - Superman II (2-Disc Special Edition)
5 - Superman II: The Donner Cut (1-Disc)
6 & 7 - Superman III (2-Disc Special Edition)
8 & 9 - Superman IV: The Quest for Peace (2-Disc Special Edition)
10 & 11 - Supergirl (2-Disc Special Edition)
12 & 13 - Superman Returns (2-Disc Special Edition)
Though that only makes 13. Maybe there will be an additional bonus disc that covers all the films with a documentary? In any case, while we can enjoy the recent batch of Superman discs for now (that Rikter and DFNYC have spread) it's nice that they'll finally be getting "Special Edition" treatment.