Hi Peter,
With regards to exporting the Diagram into Image format, we do not have support to export Diagram as image at present. The API’s for converting as images are not available in Silverlight. However, there is a codeplex project that supports exporting Visual elements into image file. We have provided the sample and a Link to this tool. Please refer to them from the attachment.
Codeplex project Link:
http://imagetools.codeplex.com/wikipage?title=Write%20the%20content%20of%20a%20canvas%20to%20a%20filePlease let us know if you have any further queries and we will be happy to help you out.
Regards,
Ramya
ExportintoImage_4e35cdb4.zip