With Marvel's Avengers characters getting their own movies before combining forces in 2012, is it possible that DC has the same plan for its Justice League characters? Right now Green Lantern is the only league-related movie currently in development, so MTV asked Green Lantern screenwriter Marc Guggenheim about the possibility of cameos from Superman or any other DC character:
Honestly, it changes on a daily basis. Whatever information I gave you today would be obsolete in a week, and maybe come back again in two weeks. And even if it wasn't in flux at the script stage, it would still be constantly in flux because you can film it, put it in the original cut, and eventually it could end up on the editing room floor. I will say, all the Easter eggs and the cameos that I put in, I couldn't even begin to predict at this point which ones will stay and which ones will go.
So the answer is a definite "maybe." Guggenheim has previously admitted that he thought the Robert Downey Jr. cameo in The Incredible Hulk was "awesome." And if DC does want to make Justice League movie, Green Lantern is where they need to start.