There's a lot to recommend Gus Van Sant's Milk on political and historical grounds. But for reasons both diverting and serious Sean Penn's smile binds it together and lifts it up. Penn's performance as Harvey Milk is a wonder all around -- he is by turns impassioned, thoughtful, mischievous -- but his face-stretching, joyful smile pushes the limits of what one facial expression can accomplish in a performance. In moments both personal and political, that ...