Here, Henin is about to hit a powerful topspin forehand from an almost fully open stance. A downward tilt of the stringbed is common to almost all topspin forehand backswings, and with Justine's grip, slightly west of Semi-Western, we would usually see a bit more of a downward tilt. The racquet face will naturally rotate into a vertical plane by the time it reaches the ball.
The layback of Justine's wrist will enhance the forward and upward whip of her racquet head as she swings.
Especially evident in this photo are two of Justine's other great assets: ferocity and focus.