Freeze dried movies says that the villains will be Carnage, Lizard and Black Cat:
Our regular scooper tells FreezeDriedMovies that plans are underway for Spider-Man 4, which were (obviously) set up in the third film. In the third entry, Dr. Curt Connors (played by Dylan Baker) looks at a piece of symbiote with Peter Parker. The movie then travels along it's path without another mention of that "piece" of symbiote. This is the set up for Spider-Man 4 where that small piece of alien symbiote becomes CARNAGE. Yes Cletus Kasady is coming to the big screen, one of Spider-Man most horrifying and evil villains. Not only with Parker have to deal with the red lean mean killing machine, but Connors is set to become the long awaited LIZARD! these two villains have all been CONFIRMED for Spider-Man 4. There is talk of the Black Cat making her first appearance, but that's all but official.
So there you have it. Spider-Man, The Lizard, Carnage... and hopefully NO Sam Raimi. Avi Arad, please find someone who CARES what the fans think!