Two different film projects focusing on Princess Diana are currently in discussion.
Pathe Films (who produced Keira Knightley in The Duchess and Helen Mirren in The Queen) are reportedly hoping to cast both actresses in a biopic of Diana. It would focus on Diana's early years as a princess, her marriage to Charles and her death in Paris. Keira would be cast as Princess Di and Dame Mirren would be Frances Shand Kydd, Di's mother.
A second film (by Bafta-winning producer Stephen Evans) would see Charlize Theron cast as Princess Di with Ewan McGregor portraying Ken Wharfe, Diana's bodyguard of 8 years.
Passing this information on for those interested but I have to say that I am not fond of either of those actresses being cast as Princess Di. Please... no.