The movie was originally planned to be based on the Macross Saga. Here are a few updates (from: "Anime Expo 2008: Robotech". Anime News Network (2008-07-05) and Spider-Man & Smallville Writers for Robotech")
"During the Robotech Panel at Anime Expo 2008, the involvement of Tobey Maguire and Lawrence Kasdan was confirmed, with Kasdan writing the script for the live action movie. Tommy Yune also revealed that the movie is planned as a re-imagining of the original Robotech universe (with new updated mecha and character designs) and will take place several years in the future, departing from the original cartoon's 2009 setting. As of November 2008, Alfred Gough and Miles Millar are the set writers for the film."
Movie designs leaked out. Designs for the Zentraidi Mecha looks absolutely cool!
Beyond Hollywood said that Tobey Maguire will produce but may not star in the movie. There are rumors that he'll be Rick Hunter.