Question:
setFlash() no longer showing up on the page. Why ?
$this->Session->setFlash("Hello world");
Answer
As of CakePHP version 1.2 you need to tell the template where to put the flash message
<?php
$session->check('Message.flash')) {
$session->flash();
}
?>

You no need to check do a checking before flashing a message.
$session->flash() will take care for u ^^
I found my CakePhp 1.1 project had exactly this code in the layout, so I didn’t need to add it.