Output to the page within Zend PHP engine:
$writer = new Zend_Log_Writer_Stream('php://output');
$logger = new Zend_Log($writer);
$logger->log('Enjoy this test', Zend_Log::DEBUG);
Or to the webserver error log:
$writer = new Zend_Log_Writer_Stream('php://stderr');
$logger = new Zend_Log($writer);
$logger->debug('Beginning log');