Feeds: Hook after Import done
I have never used this, but you can try hook_feeds_after_import.  You will likely need to kpr the $source parameter to the hook.

You may also be able to something with Rules.  Feeds events don't appear in Rules (unless there is a module I don't know about), but you may be able to trigger on the node save and update events filtered to the content type(s) that you are importing to.