According to The LA Times, Jolie has been interested in Maleficent since last spring, but in the last few weeks has become really keen to sign on to play the Mistress of all Evil. The Times notes that she doesn't have a film ready to go after she finishes The Tourist, which might make her free to sign up with Disney. It's still all rumor and conjecture at this point, as the film doesn't even have a script or director. (And I'm still hoping it won't be Burton. Yes, count me among Maleficent's fervent fans.)
For someone whose name has become synonymous with "large family", Jolie hasn't done a lot of family-friendly movies in her career. I could see why she would be interested in signing up with Disney, though it's typical that she wouldn't choose a light-and-fluffy film, but something Gothic and postmodern. She would be the ideal Maleficent though. Look at her bone structure! Wouldn't it be perfect for green foundation and twisty horns?