How to determine what current basemap is?

[KirkKuykendall]

Map.xml contains an IsBaseMap property.  Is there anything in the Viewer SDK that exposes what the current basemap is?

<esri:ArcGISTiledMapServiceLayer ID="Topographic" Url="http://services.arcgisonline.com/ArcGIS/rest/services/Ocean_Basemap/MapServer" MinimumResolution="0">
    <esriExtensibility:Document.IsBaseMap>true</esriExtensibility:Document.IsBaseMap>
    <esriMapping:LayerExtensions.LayerName>Ocean</esriMapping:LayerExtensions.LayerName>
    <esriMapping:LayerExtensions.LayerInfos />
    <esriExtensibility:LayerProperties.IsPopupEnabled>true</esriExtensibility:LayerProperties.IsPopupEnabled>
    <esriExtensibility:LayerProperties.IsVisibleInMapContents>true</esriExtensibility:LayerProperties.IsVisibleInMapContents>
  </esri:ArcGISTiledMapServiceLayer>

Thanks!

[KirkKuykendall]

Resolved by looping through all layers and calling ESRI.ArcGIS.Client.WebMap.Document.GetIsBaseMap.