It’s very common practice in the comic industry to release trade paperbacks of key issues around the time of a new movie to both introduce new readers to the characters and cash-in on the hype. Often, the issues that relate directly to the storyline in the movies are focused on such as origins or major crossovers.
In the case of The Dark Knight Rises, there are very strong rumors that a big part of the story is taken from Knightfall. The 90s Batman crossover that followed the Death of Superman storyline saw Bane gaining comic immortality as being the man who finally, literally, broke the Bat by snapping Batman’s back like a twig. Bruce Wayne spend the next year or so in a wheelchair as Azrael became a new and more violent Batman.
Apart from all of the rumors of what happens in the movie, DC has re-released a new version of the first volume of the Knightfall trade this week featuring never before reprinted chapters from the crossover. It could just be a coincidence, but with the possibility that the new movie draws from this crossover…the timing is definitely interesting.