Edge Award for Interactive Innovation acceptance video. Specifically, the dev clarifies that, "There will be no insertion of Campaign objects, enemies or friendlies via the Forge as folks have speculated." Okay then. What else? Oh, yeah, no "new feature that implements Campaign objects into multiplayer" is in the works, either.
Seriously, folks ... let's be more ambitious with our rumors! The video is clearly hinting at the fact that Halo 4 won't be developed by Bungie, or even Gearbox, but by gamers themselves. That way, if you don't like the story or missions, you'll have no one to complain to but yourself.