Well, it's not surprising that it looks like Electro will be the villain in The Amazing Spider-Man 2, as rumors to that effect have been circulating for awhile. What is surprising is who is in talks to play Electro.
According to Variety, Sony is in early talks with Jamie Foxx to play the villain in The Amazing Spider-Man 2. In the comic books, Electro is a supervillain with the power to control elecricity. He's one of Spider-Man's earliest villains, having first appeared all the way back in The Amazing Spider-Man #9.
Back in July, Comicbook.com speculated that the Amazing Spider-Man after the credits scene could be hinting at Electro as the villain, because the mysterious figure appeared and disappeared with the crackle of lightning. The Amazing Spider-Man 2 is set to arrive in theaters on May 2, 2014.