MapLayer Class

<UserControl x:Class="SilverlightTest1.ShapeSnippets"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:m="clr-namespace:Microsoft.Maps.MapControl;assembly=Microsoft.Maps.MapControl"
    Width="1024" Height="768">
    <Grid x:Name="LayoutRoot" Background="White">
        <m:Map x:Name="TestMap" CredentialsProvider="Your Key" Mode="AerialWithLabels"  Grid.Column="0" Grid.Row="0">
            <m:Map.Children>
                <m:MapLayer>
                    <m:MapLayer.Children>
                      <m:MapPolygon Fill="Red" Stroke="Yellow" StrokeThickness="5"
                                  Opacity="0.7" Locations="20,-20 20,20 -20,20 -20,-20"/>
                      <m:MapPolyline Stroke="White" StrokeThickness="5" Opacity="0.7"
                                   Locations="10,-10 10,10 -10,-10 -10,10"/>
                    </m:MapLayer.Children>
                </m:MapLayer>
            </m:Map.Children>
        </m:Map>
    </Grid>
</UserControl>