I was actually shocked that Miranda was working with Bane.
I've heard more than one person say this.
I'm actually amazed some people remained unspoiled on this point. I actually didn't read the hidden spoiler portions of the relevant posts, but I could tell what had happened just from the flavor of people's reactions.
I thought that this was kind of an "open secret" about the film, but then again I probably don't do enough to avoid spoilers.