I'm on a Mac OSX 10.7.3 with Eclipse 3.7.2 and when I create the BPMN diagram, the matching image file is not created. Is there a setting that must be modified after installation? I did not have any setting options show up in the Eclipse preferences for the "Activiti->Save" section.
In 5.9.0 the automatic generation of an image was removed from the release because it didn't work well with the Explorer images. But you can still manually create an image by right-clicking on the diagram and choose export.