In regards to Dark Knight Rises. I don't follow fan forums, but I have some theories that are probably correct and probably will be considered spoilers. So don't read on if you don't want to be spoiled.
Well before they even green lit the third movie, it always made logical sense to me to bring back Liam Neeson's Ra's Al Ghul character and his ninja "league of shadows" for the last movie of the trilogy. He's a ninja... he could have easily escaped that train crash. And all the fans know that in the comics Ra's Al Ghul is immortal. Too easy for that not to happen. Nice shock moment for the movie and it ties everything together.
That said, in the first movie they combined the "Ra's Al Ghul" character with the character Henri Ducard
http://batman.wikia.com/wiki/Henri_Ducard ... Ducard was Neeson's first identity in "Batman Begins" before he reveals himself to be the real Ra's Al Ghul. In the comics, Ducard teaches a young Bruce how to be a detective. Ducard is French. We know that Marion Cotillard is playing some character called "Miranda Tate". Marion Cotillard is French. Therefore, I'm guessing that Marion Cotillard playing Ducard/Ra's Al Ghul's daughter... Talia Al Ghul (eventual love-interest to Bruce who has his son).
That's just my guess. I also think it's possible Joseph Gordan Levitt could be some version of Nightwing (I remember Nolan saying they would never include Robin... but a Nightwing-esque character doesn't seem too off the table) and Batman might end up dying/have his back broken... but I came up with this independent of any fanboy forums. SO i'm sorry if it's well established stuff. I could see Bruce Wayne dying, but Batman "living on" (maybe that's the purpose of Gordon Levitt's character).