Signavio closely collaborates with the Hasso-Plattner-Institute regarding the implementation. The BPMN 2.0 editor is now presented to the community in the context of the Signavio-Oryx Academic Initiative.
You will get a good first impression of the BPMN 2.0 editor through this screencast. It shows all three diagram types (conversation diagrams, choreography diagrams and process/collaboration diagrams) as well as the reuse of terms across different diagrams using the Signavio glossary functionality.
So far, the presented editor is in alpha stage. The productive version will be made available to Signavio customers later this year, including migration paths from many BPMN 1.x tools.