Silverlight Obtaining transformed UIElements screen size...

// Obtain transform information based off root element
GeneralTransform gt = element.TransformToVisual(Application.Current.RootVisual);

// Find the four corners of the element
Point topLeft = gt.Transform(new Point(0, 0));
Point topRight = gt.Transform(new Point(element.RenderSize.Width, 0));
Point bottomLeft = gt.Transform(new Point(0, element.RenderSize.Height));
Point bottomRight = gt.Transform(new Point(element.RenderSize.Width, element.RenderSize.Height));