I think Mark Hughes is right when he says the fight will be built up to and most likely take place toward the end of the film. Anything else would simply be a waste of potential for suspense, tension, etc. You can't shoot your wad too soon. It's hard to get more dramatic and potentially epic than the two most iconic superheroes of all time facing off.
I'm a Batman fan first, but for the sake of Superman fans I hope it's handled with care and that both get their moments to shine.
I have a feeling they're going to play it out in such a way that it causes people to argue over who
really won and keep the debate going. Superman's not going to look like a chump. There might be a moment where he clearly has the upper hand, shows mercy and then Batman takes advantage, etc. I don't think we'll be done arguing over who would actually win in a fight after the movie comes out. That argument will never end and Goyer and Snyder should know that.