Bleeding Cool have previously noted how scenes from All Star Superman by Grant Morrison and Frank Quitely turn up in the movie, and it seems DC noticed too, as they are giving away the first issue, in print and digitally, on that day, in a "Special Edition". Retailers will receive copies based on their orders for Action Comics #20 and can then order extra copies if they wish at an incremental cost.
They'll also have the previously announced promotional posters and bags tied into the movie. It's also the release date for Scott Snyder and Jim Lee's Superman Unchained, which will be the biggest seller for the month. It just will.
US libraries will also be participating, giving away comics, badges and bookmarks, and a Digital Superman sale, with the likes of Superman For Tomorrow, Superman Earth One and Superman Birthright will start two days before.