The news from The Hollywood Reporter is that fan favorite Brian K. Vaughan is writing a screenplay for the teen-centric property, which will have Kevin Feige as a producer. Vaughan created the series with Adrian Alphona and wrote the series from its 2002 launch as part of Marvel's hit-and-miss manga-inflected Tsunami line until Joss Whedon came on board in April 2007.
This film will fall under Marvel's independent production slate, and is not likely to bow before 2012 given the films Marvel already has announced for production. So like "Ant-Man," fans waiting for this one should probably be patient.
Vaughan, represented by the powerhouse Creative Artists Agency, also has "Y: The Last Man" in development at New Line. It's considerably too early to look at casting possibilities, as that would be determined by a script that hasn't been written yet.