Telltale just made a post on Twitter announcing the release dates for The Walking Dead: Season Two Episode 1: All That Remains.
It will release later today for PC and Mac (through the Telltale Store and Steam) and for PlayStation 3 in North America. It will then release tomorrow worldwide for Xbox 360. The iOS version will be coming later this week. The European PlayStation 3 release date, as well as the release dates for the Vita and Ouya versions have not yet been set.
Source: Telltale Twitter