Ra's al Ghul is my favorite villain in the DCUniverse. I just love the idea of a global ecoterrorist as a Batman villain. I feel like he was done great justice in Batman Begins, but I could not be more thrilled to know that we will see MORE of him in the next film. Now, whether that will be in a flashback or current scene, it doesn't matter....more Ra's al Ghul is a great thing (especially portrayed by Liam Neeson).
If we could find out that he was behind Bane, or at least involved in Bane's training (seems incredibly likely) it would be very cool. I would also love to know that, if he is revealed to have SURVIVED the first film, to know that he has been watching the situation unfold in Gotham, and has watched Bruce's now 9-10 year career as Batman. That would just be a cool moment. Bruce and Ra's fought each other as student and teacher, now they would meet as equals and Ra's would have that respect for Bruce that he has always had for him in the comics. Man, I just love these characters and the dynamics between them.
-R