And the Winner for Best Supporting Actress is...

Mary-Kate Olsen in Factory Girl!!! Mollygood has this little clip of MK's cameo in FG starring Sienna Miller. And by cameo I mean, an extra. This apparently is her entire role! If you blink you will miss her. So keep your eyes open. She's standing in the back in some black dress. Honestly, she probably puts in a more riveting and honest performance than Sienna!