Here is a screengrab from the casting site, Autumn Frost (via Superman Homepage) which has been set up. Using a code-name during filming has become pretty common with big movies like this one...The Avengers for example is known as "Group Hug", while Captain America: The First Avenger was called "Frostbite". Be sure to click on the link at the bottom of the page to apply to be an extra on "Autumn Frost" (a code name out very own DCMarvelFreshman revealed would be used back in March) and keep an eye out for that when they begin filming later this year!
Starring Henry Cavill as Superman, Amy Adams as Lois Lane, Kevin Costner as Jonathan Kent, Diane Lane as Martha Kent and Michael Shannon as General Zod,
Superman: The Man of Steel is expected to be released sometime during the Winter of 2012!