gistfile1.cs

public static XElement RemoveAllNamespaces(XElement e)
{
    return new XElement(e.Name.LocalName, (
        from n in e.Nodes() 
        select((n is XElement) ? RemoveAllNamespaces(n as XElement) : n)), 
        (e.HasAttributes) ? (from a in e.Attributes()
                             where (e.Attributes().Where(ah => a.Name != a.Name.LocalName && ah.Name == a.Name.LocalName).Count() == 0) 
                             select new XAttribute(a.Name.LocalName, a.Value)) : null);
}