First of all, yes, I know that just because something happens in a movie doesn't necessarily mean it will happen in the comics (particularly for a non-Marvel Studios production). However when new Spider-Man films open, we seem to get the heavily publicized villain appearing in the comics. (We had an arc with the Lizard when the first Amazing film opened, Electro is a villain in the early issues of the relaunched Amazing comic, etc.)
So... Harry Osborn... He was in Amazing Spider-Man 2 as a villain. And while he wasn't as heavily promoted as Electro, he certainly made a bigger impact in the film. It was also heavily foreshadowed that he would be leading a version of the Sinister Six for Amazing Spider-Man 3.
The question now is... How will this impact Harry's return in the comics? Will he once again fall from grace? Or has he truly risen from the shadows of his past?