Norton has been enthusiastic about returning to the role, despite butting skulls with Marvel over the final cut of Incredible Hulk, but Marvel may be once-bitten, twice-shy on the notoriously controlling actor. The rumor is that Marvel is picking an unknown for the role of Bruce Banner aka the Hulk, and unveiling that actor at San Diego Comic Con this month, despite Norton meeting with potential Avengers director Joss Whedon to talk about his character's place in the film (most assume the hunt for Hulk will unite the Avangers in the movie, the same way it happened originally in the comics).
I think most fans never expected Norton to return to the role, in large part due to how unhappy he seemed with Incredible Hulk, and it wasn't until Marvel Studios exec Kevin Feige addressed it that it even seemed like a possibility. I always assumed the role would be recast, until Marvel said that the door was still open and Norton talked about it a little at SXSW. Yes, they both got my hopes up, but it wouldn't be the first time we've seen a new Hulk. The character just can't seem to catch a break.