The Wolf Among Us: Episode 2 - Smoke and Mirrors is out now on the Telltale Games store, Steam, and on PlayStation Network and Xbox Live Arcade. It is scheduled to be released for iOS some time later this week.
However, note that there's apparently a problem with season passes on XBLA, where the system will not let you download episode 2 if you purchased a season pass. Do not click to buy episode 2, as you will be charged twice. Microsoft updated their Xbox live status page stating that they are working on it now, and should have a fix out by tomorrow.