I was not thinking that the coordinate system that I was using would lay an evenly spaced grid but it does so I was able you use the following solution:
List<ESRI.ArcGIS.Client.Geometry.Polyline> polylineList = new List<ESRI.ArcGIS.Client.Geometry.Polyline>();
for (int lat = -90; lat <= 90; lat += 10)
{
ESRI.ArcGIS.Client.Geometry.PointCollection pointCollection = new ESRI.ArcGIS.Client.Geometry.PointCollection();
pointCollection.Add(new MapPoint(-180, lat));
pointCollection.Add(new MapPoint(180, lat));
ESRI.ArcGIS.Client.Geometry.Polyline polyline = new ESRI.ArcGIS.Client.Geometry.Polyline();
polyline.Paths.Add(pointCollection);
polylineList.Add(polyline);
}
for (int lon = -180; lon <= 180; lon += 10)
{
ESRI.ArcGIS.Client.Geometry.PointCollection pointCollection = new ESRI.ArcGIS.Client.Geometry.PointCollection();
pointCollection.Add(new MapPoint(lon, -90));
pointCollection.Add(new MapPoint(lon, 90));
ESRI.ArcGIS.Client.Geometry.Polyline polyline = new ESRI.ArcGIS.Client.Geometry.Polyline();
polyline.Paths.Add(pointCollection);
polylineList.Add(polyline);
}
GraphicsLayer graphicsLayer = Map.Layers["GridLines"] as GraphicsLayer;
foreach (ESRI.ArcGIS.Client.Geometry.Polyline polyline in polylineList)
{
Graphic graphic = new Graphic()
{
Symbol = LayoutRoot.Resources["DefaultLineSymbol"] as Symbol,
Geometry = polyline
};
graphicsLayer.Graphics.Add(graphic);
}