Have a module function hooking batch:

  $batch = array(
    'operations' => array(
      array('mymodule_batch_task', array($var1, $var2)),
    ),

    'finished' => 'mymodule_batch_finished',
    'title' => t('batch process'),
    'init_message' => t('starting.'),
    'progress_message' => t('Processed @current out of @total.'),
    'error_message' => t('encountered an error.'),
    'file' => 'mymodule.admin.inc',
  );
  batch_set($batch);

The batch process messages appear on the screen as they should, but it seems that the operations function doesn't fire at all. I put a watchdog command before the above call, and it appears in the dblog report. I put a watchdog call at the beginning of mymodule_batch_task() and it doesn't show up, and neither does the watchdog call from the 'finished' function.

Jeff