I just saw this post on the SharePoint forums: http://social.msdn.microsoft.com/Forums/en-US/sharepointgeneral/thread/e9cd9836-5a50-42b3-bf2f-02338a3168f3 – it appears that there’s a possibility for data corruption when using the STSADM mergecontentdb command. The post details a few things you can do to reduce the possibility of corruption when using the command but it would appear that the hidden message is to use Backup/Restore until a fix is released.