How can you clone a WPF object?

In .NET 4.0, the new xaml serialization stack makes this MUCH easier.

var sb = new StringBuilder();
var writer = XmlWriter.Create(sb, new XmlWriterSettings
{
    Indent = true,
    ConformanceLevel = ConformanceLevel.Fragment,
    OmitXmlDeclaration = true,
    NamespaceHandling = NamespaceHandling.OmitDuplicates, 
});
var mgr = new XamlDesignerSerializationManager(writer);

// HERE BE MAGIC!!!
mgr.XamlWriterMode = XamlWriterMode.Expression;
// THERE WERE MAGIC!!!

System.Windows.Markup.XamlWriter.Save(this, mgr);
return sb.ToString();

The simplest way that I've done it is to use a XamlWriter to save the WPF object as a string. The Save method will serialize the object and all of its children in the logical tree. Now you can create a new object and load it with a XamlReader.

ex: Write the object to xaml (let's say the object was a Grid control):

string gridXaml = XamlWriter.Save(myGrid);

Load it into a new object:

StringReader stringReader = new StringReader(gridXaml);
XmlReader xmlReader = XmlReader.Create(stringReader);
Grid newGrid = (Grid)XamlReader.Load(xmlReader);