Maggie Gyllenhaal's cast in Batman: The Dark Knight

Maggie Gyllenhaal is set to replace Katie Holmes in the new Batman movie. Maggie Gyllenhaal arrives for the 79th Annual Academy Awards at the Kodak Theatre in Hollywood, California Sunday 25 February 2007. EPA/SEAN MASTERSON

Maggie Gyllenhaal arrives for the 79th Annual Academy Awards at the Kodak Theatre in Hollywood, California Sunday 25 February 2007. EPA/SEAN MASTERSONThe 'Mona Lisa Smile' actress is involved in talks to star opposite Christian Bale in 'Batman: The Dark Knight'.Maggie, 30, will take the role previously played by 'Dawson's Creek' actress Katie Holmes.Katie - who starred as Rachel Dawes in 'Batman Begins' - announced her plans to drop out of the project last January.Heath Ledger will star as supervillain The Joker, while Aaron Eckhart will play crime boss Two-Face.Meanwhile, Maggie has bought fiancé Peter Sarsgaard a diaper bag for his 36th birthday.The actress was spotted buying the Flison Rucksack bag from Earnest Sewn while doing some last-minute shopping in New York's Meatpacking District on the afternoon of his birthday (07.03.07). Maggie, 30, reportedly hoped her actor boyfriend would use the rucksack as a diaper bag for the couple's five-month-old daughter Ramona.A source said: "She said there was a party for Peter later in the evening. She was also interested in a shirt her brother Jake purchased a week before, but the store was sold out in Peter's size."Maggie and Peter met on the set of 2003 movie 'In God's Hands' - a low-budget feature film that was never released.(C) BANG Media International