<?php

function path_redirect_newest_menu() {
  $items['media/gallery'] = array(
    'page callback' => 'path_redirect_newest_gallery',
    'access callback' => TRUE,
  );
  return $items;
}

function path_redirect_newest_gallery() {
  $query = new EntityFieldQuery();
  $query->entityCondition('entity_type', 'node')
    ->entityCondition('bundle', 'gallery_album')
    ->propertyCondition('status', 1)
    ->propertyOrderBy('created', 'DESC')
    ->range(0, 1);

  $result = $query->execute();
  $node = $result['node'];
  reset($node);
  $nid = key($node);

  drupal_goto('node/' . $nid);
}