Nolan is only producing it as he will be busy with the third Batman film. Zod is only a rumour at the moment as nothing has been confirmed about the film. I found a quote from Zack Synder from the Moviehole website:
"Zack Snyder has confirmed Fleming's report, telling said scribe ''I've been a big fan of the character for a long time, he's definitely the king of all superheroes, he's the one. It's early yet, but I can tell you that what David [Goyer] and Chris [Nolan] have done with the story so far definitely has given me a great insight into a way to make him feel modern. I've always felt he was kind of awesome. I'll finish 'Sucker Punch' and get right at it."