LatinoReview that Viggo Mortensen will not be joining Superman: Man of Steel. It had be reported that Viggo had been up for the role of Zod along with Daniel Day-Lewis. ThePlaylist is hearing "whispers" that Snyder wants to reunite with Gerard Bulter (300, Gamer, RockNRolla) and he could end up in the movie.
Butler is great on screen when there is a decent script and solid director behind him. It would be interesting to see him play Zod or other possible villains. Nothing is confirmed or even mentioned by the trades so it's just wishful thinking at this point.