On keeping the Scrap nodes, could we ( maybe ) add "Do not erase" button to the scrap board and call it Blackboard? If the button is clicked, the conversation stays around. It then works similar to any other node in the system. A new scrap board conversation can be started just like a new Question is opened. Normal conversation around any given node flows like normal.
in reply to "Whiteboard Nodes"
When the Do Not Erase button is not clicked ( or unclicked, for that matter ), some maintenance process will delete it
automagically. Preferably in a well defined time frame - say the culling process would run about the same time that votes are refreshed.
It may be worthwhile to consider a maximum life span. Anything left on the Blackboard for more than, say, 7 days will be culled. That will prevent the area from getting too cluttered and still give us time to mull over any questions
and to properly consider the answers given.