I recently learned how to rotate a BitmapImage using the \'TransformedBitmap\' and \'RotateTransformed\' classes. Now I am able to perform clockwise rotations on my images. But
To give your flip a little more "depth" so that is looks more like a true flip you probably want to do a skew transform with a smaller scale transform.
You would want to skew the object about 20 degrees to make it look as if it is flipping in 3D. This is a poor mans 3D flip. You can accomplish a true 3D flip in WPF but that takes a bit more work.
This will give you the animation that looks cleaner, then you can toggle visibility on two different panels to give the impression of a front and a backside to your element.