Unfortunately Whedon didn't reveal any additional information about the film, due out in 2012. It's assumed that during the Marvel panel on Saturday Whedon and Marvel will announce the cast of The Avengers -- hopefully with a Bruce Banner cast (maybe Adrien Brody? Maybe not.) and ... an Ant-Man, perhaps? During today's Masters of the Web panel, Edgar Wright (the assumed director) shot down all Ant-Man questions, saying no one is cast and that he hasn't really worked on the script at all this year.
So, at current count: Whedon is a go, and we're now waiting on official confirmation of the full cast and which characters will be involved. Additionally, Edgar Wright says Ant-Man has not been cast to his knowledge. Is Whedon really the guy to deliver this to the screen, or do you proceed with caution considering his big-screen experience to date?