Warner Bros. is considering Joaquin Phoenix, most recently seen falling in love with a computer in the Spike Jonze movie Her, for a role in the film widely dubbed Batman vs. Superman, Variety reports. According to sources, he could be tapped as the films antagonist, probably Lex Luthor. Whether he will receive a formal offer or accept one is another matter, as is the veracity of the rumor: after all, its only been a few months since Bryan Cranston denied being cast as the supervillain. …