Have you seen the cast list for this film, by the way? From Filmdrunk:
So we know that Shailene Woodley has joined the film as Mary Jane Watson, Paul Giamatti is playing Rhino, Chris Cooper is Norman Osborn, Dane DeHaan is Harry Osborn and Jamie Foxx is Electro. Also, Venom may or may not be introduced.
As we all know from Spider-Man 3, the later non-Chris Nolan Batman films and the greasy X-Men 3, the more characters you cram into a comic book movie sequel the better.
Three more shots after the jump: