Messaging API, custom module_invoke_all()

gistfile1.php

<?php

/**
 * Invoke hook on all modules
 * 
 * This is like module_invoke_all with some differences:
 * - The results are just merged (not recursively)
 * - The module name is added to each resulting array
 * 
 * @param $hook
 *   The name of the hook to invoke.
 * @param ...
 *   Arguments to pass to the hook.
 * @return
 *   An array of return values of the hook implementations. If modules return
 *   arrays from their implementations, those are merged into one array.
 */
function messaging_module_invoke_all() {
  $args = func_get_args();
  $hook = $args[0];
  unset($args[0]);
  $return = array();
  foreach (module_implements($hook) as $module) {
    $function = $module .'_'. $hook;
    $result = call_user_func_array($function, $args);
    if (isset($result) && is_array($result)) {
      foreach ($result as $key => &$value) {
        if (is_array($value)) {
          $value += array('module' => $module);
        }        
      }
      $return = array_merge($return, $result);
    }
    else if (isset($result)) {
      $return[] = $result;
    }
  }

  return $return;
}