I'm helping @OverHere administer their board, and this evening, it looks like xf_node has been emptied. I've checked the Admin log, and there are no actions in there to delete the nodes. All the posts are still there, and also the threads are still there, referencing the old node_ids. All that has been done with the site from the logs, is XenPorta and XenTag updated, and neither of those touch the xf_node table. I can manually create a new node, and edit the database to assign the new node_id to the thread, but that still leaves all the old node information missing.