SCI FI Wire chatted with Superman Returns co-writer Michael Dougherty who says there may be more than one villain in the sequel:
Michael Dougherty, co-writer of last year’s Superman Returns, told SCI FI Wire that the upcoming sequel will feature at least one villain drawn from the DC Comics franchise. Or more than one? “Maybe,” Dougherty said coyly in an interview on the set of his upcoming supernatural horror film Trick ‘r Treat in Vancouver, Canada, on Jan. 15. “It’s [Mr.] Myxyzptlk,” he added, with tongue in cheek.
The full interview is available at the link above in which he also says you can expect more action.
Source: SCI FI Wire