The latest man to contend for the director's chair is Martin Campbell, who's still coming off Casino Royale and just completed Edge of Darkness, also known as Mel Gibson's acting comeback. The previous candidate for the job was screenwriter Greg Berlanti, but Warner Bros. most likely chickened out of giving a tentpole comic book project to a guy with only The Broken Hearts Club to his name as a director. Berlanti's screenplay is still the one Warners is working with.
Campbell, by the way, is possibly the most inconsistent filmmaker in the business. Not only is he capable of making films that are fantastic (Casino Royale), and mediocre (Vertical Limit), and dreadful (Beyond Borders), but he can go from hugely entertaining to ass-boring within the same franchise. (I'm thinking, of course, of The Mask of Zorro and The Legend of Zorro). At least the anticipation won't bore you: you really don't know what you're gonna get.
Of course, one possibility is that Watchmen comes along and ruins all other superhero movies the way The Wire ruined all other cop shows, and then I'll care about Green Lantern about as much as I care about CSI (uh, not at all).