Hi,
thank you very much for adding the GraphViz-support to OmniGraffle. It has opened up many possibilities for using OmniGraffle part of a workflow.
Is there any plans of supporting HTML labels in OmniGraffle? HTML labels allow more versatile output format and by supporting this, OmniGraffle would be an ideal tool for further processing the generated files.
See HTML labels in
http://www.graphviz.org/doc/info/shapes.html