I was recently in a DevelopMentor course when I ran into a very interesting observation.  The XmlSerializer serializes any class that dervies from XmlNode (including XmlDocument, XmlElement, et al) as plain XML.  Previous to RTM of the .NET framework, these classes were serialized like any other class (all public properties and fields were serialized).  To our amazement (Dan Sullivan and mine), we realized that the XML classes serialized perfectly when run through the XmlSerializer class.