The taxonomy system has also been revised to work with the Field API and to give developers more hooks to interact with.
taxonomy_term_delete($term)
This hook is invoked when a taxonomy term is removed from the database. You can use this hook to update any content related to the term.
hook_taxonomy_term_insert($term)
This hook is invoked when a taxonomy term is added to the database. You can use this hook to update any content related to the term.
hook_taxonomy_term_load($terms)
This hook is called when one or more terms are loaded from the database. You can alter or add information to the terms within this hook. You should ensure that functionality executed within this hook executes quickly and that it does not interfere with the Drupal taxonomy cache. For more information, see: http://api.drupal.org/api/function/hook_taxonomy_term_load/7.