Slashfilm has discovered that Disney, who owns the rights to the Marvel properties, has purchased a domain for a possible Ant-Man movie. As they state, generally domains are bought because something is being developed. Ant-Man-TheMovie.com is probably more specific than if they were just picking up the url to protect from someone else grabbing it.
With Iron Man and Incredible Hulk already out and Thor and Captain America in development the next project in the Marvel world was expected to be Ant-Man. An Ant-Man movie would figure into The Avengers as well, though it isn’t known whether he would be introduced in the movie or just arrive for potential sequels.