Blog de Stephane Eyskens sur SharePoint

using(SPSite Site = new SPSite(URL))
{
  using(SPWeb Web = Site.OpenWeb())
  {
    SPNavigationNodeCollection Nodes = Web.Navigation.TopNavigationBar;
    foreach(SPNavigationNode Node in Nodes)
    {
      if(Node.IsVisible)...//returns always true even if the node is marked as hidden..
    }
  }
}

foreach(SPNavigationNode Node in Nodes)
{
 using(SPSite Site = new SPSite(Node.Url))
 {
  using(SPWeb Web = Site.OpenWeb())
  {
     if(PublishingWeb.IsPublishingWeb(Web))
     {
         PublishingWeb PubWeb = PublishingWeb.GetPublishingWeb(Web);
         if(PubWeb.IncludeInGlobalNavigation)
            //marked as visible
         else
            //marked as hidden
     }  
  }
 }
}