/**
 */
function _phptemplate_variables($hook, $vars) {
  //...
  $vars['args'] = $vars; //TODO: remove this debug variable.
  return $vars;
}

An easy debug trick: gives you a variable that you can print in any tpl.php to find out what vars you have available there.

Easy debug variable to find what vars are available in a tpl.php file

php, debug, template, drupal, Development

PHP