Diane Lane has signed on to play Martha Kent in the Zack Snyder-directed Superman movie.  Snyder said in a statement:

"This was a very important piece of casting for me because Martha Kent is the woman whose values helped shape the man we know as Superman.  We are thrilled to have Diane in the role because she can convey the wisdom and the wonder of a woman whose son has powers beyond her imagination."

Henry Cavill (The Tudors) will star as Clark Kent/Superman.  Charles Roven, Emma Thomas, Christopher Nolan and Deborah Snyder are producers on the film.  David S. Goyer is writing the screenplay based on a story by Goyer and Nolan.  The untitled Superman film is scheduled for a December 2012 release.  Hit the jump for more on possible stars/characters.

THR confirms that both Kevin Costner and Viggo Mortensen are circling roles in the film -- Costner as Jonathan Kent, Mortensen as General Zod.  Neither actor has fully committed yet, and it looks more and more like Mortensen will indeed sign a deal to play the Huntsman in Snow White and the Huntsman that will keep him busy during Superman production.  The filmmakers can take solace in the fact that Lane is a great get; she and Costner form the ideal on-screen Midwestern married couple.  (Costner was born in California, Lane was born in New York.  Go figure.)

It's been reported that Alice Eve, Diane Kruger, and Rosamund Pike are on the shortlist for a lead female role, later rumored to be Kryptonian villainess Ursa.  It was specified that the role in question is not Lois Lane, though she will appear in the film.

Here is the official announcement:

DIANE LANE CAST AS MARTHA KENT IN WARNER BROS. PICTURES’ AND LEGENDARY PICTURES’ NEW SUPERMAN MOVIE

BURBANK, CA, March 2, 2011 – Warner Bros. Pictures and Legendary Pictures announced today that Oscar®-nominated actress Diane Lane will play Martha Kent, the only mother Clark Kent has ever known, in the new Superman movie to be directed by Zack Snyder.

Snyder stated, “This was a very important piece of casting for me because Martha Kent is the woman whose values helped shape the man we know as Superman.  We are thrilled to have Diane in the role because she can convey the wisdom and the wonder of a woman whose son has powers beyond her imagination.”

Lane will star with Henry Cavill, who was recently announced as the new Clark Kent/Superman.

Lane earned an Academy Award® nomination for her performance in the 2002 drama “Unfaithful.”  She most recently starred in the family hit “Secretariat.”  She next stars in the HBO feature “Cinema Verite,” opposite Tim Robbins and James Gandolfini.  Lane’s long list of film credits also includes “Nights in Rodanthe,” “Hollywoodland,” “Must Love Dogs,” “Under the Tuscan Sun,” “Perfect Storm,” “My Dog Skip,” “Chaplin,” “The Cotton Club” and “A Little Romance,” to name only a portion.

Charles Roven, Emma Thomas, Christopher Nolan and Deborah Snyder are the producers of the film.  The screenplay is being written by David S. Goyer based on a story by Goyer and Nolan.  Thomas Tull and Lloyd Phillips are serving as executive producers.

Slated for release in December 2012, the new Superman movie will be distributed worldwide by Warner Bros. Pictures, a Warner Bros. Entertainment Company.