In the comics, Osborn had used his partner's incomplete notes on the Goblin serum and tested it out on Van Adder, slowly driving him insane while turning him into a weird, red demon goblin named "Proto-Goblin". The other powers given to Van Adder via the Goblin serum include large claws, talons, fangs, glowing green eyes, and near impenetrable skin. It is not clear yet how his origins will change for the film, but knowing his beginnings were at Oscorp most likely means they're setting it up for Green Goblin to appear in later sequels (perhaps as the villain in part two).
If they do stick somewhat close to the original storyline, then expect either Norman Osborn and/or his partner Mendel Stromm to be cast (perhaps secretly?) soon.
Meanwhile, Khan briefly spoke about the role to the New York Times. Check out his statements after the jump.
Khan doesn't seem to even know his character's name yet, but he did have this to say: "He's a character who, I think, was not in the comics or perhaps a minor character. I've read some pages, but the whole script hasn't been made available to me." On whether he's done any training: "You don't do training for action. You're waiting for action. You just strap yourself into a harness and go." So there ya go -- at least we know he'll be in a harness at some point.
'Spider-Man' hits theaters on July 3rd, 2012.