Very tall women risk looking like pinheads if they get a super short hairstyle. Leave the boy cuts to the pixie girls (think Wynona Ryder, French actress Audrey Tatou, Natalie Portman, Mia Farrow in Rosemary's Baby).
Some tall women can get away with short hairstyles. As Shiloh, a reader of this site, points out, the "pioneer" of the pixie cut, Audrey Hepburn, was 5'7" -- quite tall even by today's standards. And if anyone can pull off a short hairstyle, it was her. That said, onscreen, she looked quite petite.