batch_example_finished(0 should document its callbacks, $result in particular

There doesn't seem to be anywhere that explains where $results come from.

It's implied here:

    // Store some result for post-processing in the finished callback.
    $context['results'][] = $node->nid . ' : ' . check_plain($node->title) . ' ' . $operation_details;

but should really be documented and clearly explained.

(Same goes for http://drupal.org/node/180528)