Version 2.4 adds the following:

TemplateNode class
The appearance of TempaltedNodes can be customized using their Template property or the Diagram.NodeTemplate property as shown below.

<diag:Diagram>
	<diag:Diagram.NodeTemplate>
		<DataTemplate DataType="diag:TemplatedNode">
			<Border
			BorderBrush="{Binding Stroke}"
			BorderThickness="{Binding StrokeThickness}"
			Background="{Binding Brush}">

				<TextBlock
				Text="{Binding Text}"
				TextWrapping="{Binding TextWrapping}"
				TextTrimming="{Binding TextTrimming}"
				FontFamily="{Binding FontFamily}"
				FontSize="{Binding FontSize}"
				TextAlignment="{Binding TextAlignment}"
				VerticalAlignment="Center"
				HorizontalAlignment="Stretch"/>

			</Border>
	</DataTemplate>
</mf:Diagram.NodeTemplate>
</diag:Diagram> 

TemplatedNode is also useful as a base of custom node classes whose appearance is set via Xaml rather than overriding OnRender.

WmfExporter component
The WmfExporter class creates a Windows Metafile (WMF) drawing from the content of a Diagram. The exporter enumerates all graphics primitives contained in the WPF visual tree and creates corresponding WMF records. This enables custom graphics are hosted controls to be rendered in WMF too.

If anyone is interested in trying out the beta, please download this archive, which includes the updated diagramming.wpf assemblies:   

https://mindfusion.eu/_beta/wpfdiag24.zip

Stoyan