It was reported a week ago, Joss Whedon would be directing Marvel's Avengers clash, and also rewriting the film's script plus Captain Americas'. And filmmaker Edgar Wright, who was hired by Marvel sometime last year to direct an Ant-Man film, tweeted earlier something that leads to pure speculation.
Many know that Ant-Man was an original Avenger in the first issues of the comic by Stan Lee. And though the first Avengers film is in the works, it was said by the president of Marvel Studios<"
To pile on another 15 or 10, frankly more than four would be too many." when he said that, he confirmed Iron Man, Thor, Captain America, and even Hulk, so obviously the mini Avenger, Ant-Man, probably won't make an appearance in the first film.
So what this speculates that maybe the two are collaborating to get both films - Avengers & Ant-Man, on the same track, which is what many believe Joss Whedon is doing with First Avenger: Captain America, director, Joe Johnston.
With Ant-Man not having an official release date, its pretty clear that the film would have to be released after The Avengers. Also, Disney recently purchased a site domain named: "ANT-MAN-THEMOVIE.COM". Plus with all the meetings Wright has been doing lately, including re-meeting Stan lee & Iron Man 2 director, Jon Favreau, Marvel could be secretly gearing up for a 2012 release. Ant-Man Vs Spider-Man 2012: Battle of Marvel's Insects.
Since this is still speculation, this so called meeting could be exaggerated, but since it is a great speculation, I'm sure as the news travels, Edgar Wright will tweet something relating to the subject.