Structure dynamic 301 redirects
Nothing clever I can think of, but it's an interesting idea.

You can either manually setup the redirects in your .htaccess file, or there are a couple of plugins that appear to let you manually manage redirects from the control panel.

A feature request to the plugin developers might be to get them to add support to listening to an (as-of-yet non-existent) "onMoveStructuredEntry" event in Craft that automatically creates the redirect for you.