hook_menu_local_tasks() works for the top level tabs, but the secondary tabs don't seem to have an equivalent. Does anyone know how I can modify those?
$primary = menu_local_tasks(0); $secondary = menu_local_tasks(1);
It's actually not a hook, it's just a function that gathers the items while in context.
There is a hook to alter the items: http://api.drupal.org/api/drupal/modules%21system%21system.api.php/function/hook_menu_local_tasks_alter/7