in reply to Hidden updates ;-(
The original node in each discussion thread were updateable. If it is updated, the original would be automatically copied and made the "root" node of the (presumable existing) discussion. The edited version would be presented at the top of the page, as the original node is now. That way, continuity would be maintained within the discussion, but the root node could be edited to become more accurate and useful, sort of a summary of the accumulated contributions to the discussion.