Paramount Pictures is bankrolling the project, which does not yet have a title or a completed script, following a flurry of interest from a number of studios. It's not hard to see why Ruzicka's story appealed to them - she is one of the few Americans to have demonstrated heroic qualities in an Iraq war that has otherwise been notable for political failures, deceptions and an unbroken cycle of violence.
Hollywood had, in fact, expressed an interest in Ms Ruzicka while she was still alive. Paramount optioned the rights to her life story last summer, and also bought up a proposed autobiography that she was planning to write with a friend, Jennifer Abrahamson. Ms Abrahamson plans to publish the book on her own.
Being mythologised by Hollywood may be a fitting testimony to a woman who, to her friends and acquaintances, always seemed larger than life. Buzzing with energy despite being young, short and almost painfully thin, Ms Ruzicka made a deep impression on journalists, fellow relief workers, politicians and grant writers from wealthy foundations. Patrick Leahy, a Democratic Senator and key ally in Washington, once said she was "as close to a living saint as they come".
Ms Ruzicka founded Civic, the Campaign for Innocent Victims in Conflict, which sought to quantify the number of civilian dead from the wars in Afghanistan and Iraq and then seek financial compensation for their bereaved relatives.
The work of interviewing relatives and collecting data on the injured and the dead was painstaking, emotionally draining and often dangerous. Having first travelled to the Middle East and central Asia with barely a penny, Ms Ruzicka became adept at raising funds from the likes of George Soros's Open Society Institute. Thanks to Senator Leahy, she also obtained almost $30m (£17m) from the US government for reparations payments.
She was a surfer girl in California, but became drawn to political activism via the San Francisco-based group Global Exchange. Over time, she drifted away from Global Exchange's idealistic campaigning for peace and decided she would rather engage with the power-brokers than simply stand on a street corner and protest against them.
In war zones, she proved so fearless that members of the marines nicknamed her Cluster Bomb Girl - for her willingness to visit the site of bombings and then badger the military into making the areas safe for civilians living near by.
She and her driver were killed in a suicide bombing on the airport road into Baghdad on 16 April this year - a shocking end to a short life (she was 28) that inspired tributes and lengthy newspaper articles around the world. Memorial services were held in New York, Washington, San Francisco, Baghdad and Kabul.
Dunst, meanwhile, is one of Hollywood's most accomplished actresses. She will come to the part of Marla Ruzicka from two different projects. In the first, out next year, she plays Marie Antoinette in a film directed by Sofia Coppola. And in the second, due out in 2007, she will reprise the role of Mary Jane Watson for the third instalment of the Spider-Man series.