Notifications event help?

I've still had no luck with this. Is there anyone familiar with the notifications framework who could help?
'twould be much appreciated :)

Thanks,
Peter

Hey pathfinder, that's probably it!

I actually ended up using the Messaging Framework directly to send my messages, because when I thought about it, nobody needed to subscribe to the particular event as such. A message only needed to go to the assignee of a task (basically, "someone has assigned a task to you").

I was a bit confused as to how the Messaging Framework and Notifications actually tied together when I posted this, but the documentation was updated afterwards and made things a lot clearer!

Jeff, as I haven't implemented Notifications as such, I'm not sure if my code does exactly what you're after, but I do act upon changes to a CCK User Reference field and send a message to the user that's selected.
That's was just a case of implementing hook_nodeapi for the "update" operation and checking the node object to see if the field has been changed.

Here are some code snippets:

/**
 *  This is just a helper function called by my hook_nodeapi
 *  It's called when $op is 'update' and $node->type is 'list_task'
 */
function kairn_nodeapi_update_list_task(&$node, $a3, $a4) {
		
	$original = node_load($node->nid);

	// check whether it's been reassigned
	if ($node->assignee != $original->assignee)
	{
		// send notification to user
		_notify_assignment($node, $node->assignee);
	}
}

function _notify_assignment($node, $assignee) {

	if ( function_exists('messaging_message_send_user') ) {
		
		$text = array();
		
		// build the message
		$text['type'] = 'kairn-node-assigned';
		$text['subject'] = messaging_message_part('kairn-node-assigned', 'subject');
		$text['body'] = messaging_message_part('kairn-node-assigned', 'main');
		
		$objects['user'] = user_load($assignee);
		$objects['node'] = $node;
		$objects['global'] = NULL;
						
		// replace all tokens
		$message = token_replace_multiple($text, $objects);
		// send it
		messaging_message_send_user( user_load($assignee), $message);
	}
}

/**
 * This just defines custom message types, templates as per Messaging Framework documentation
 */
function kairn_messaging($op, $arg1 = NULL, $arg2 = NULL, $arg3 = NULL, $arg4 = NULL) {
  switch ($op) {
    case 'message groups':
      $info['kairn-node-assigned'] = array(
      	'module' => 'kairn',
      	'name' => t('Node assignment'),
      	'description' => t('Notification of item being assigned to a user'),
      );
      return $info;
      
    case 'message keys':      
      $type = $arg1;
      switch ($type) {
        case 'kairn-node-assigned':
          return array(
            'subject' => t('Subject for milestone reminder'),
            'header' => t('Header for milestone reminder'),
            'main' => t('Content for milestone reminder'),
            'footer' => t('Footer for milestone reminder'),
          );
      }
      break;
      
    case 'messages':
      $type = $arg1;
      
      if ($type == 'kairn-node-assigned') {
      	return array(
      		'subject' => t('Assignment notification from [site-name]'),
      		'header' => t("Greetings,"),
      		'main' => array(
      			t('A [type-name] has been assigned to you. '),
      			t('View this [type-name] at [node-url]'),
      		),
      		'footer' => array(
      			t('This is an automatic message from [site-name]'),
      		),
      	);
		}
		
      break;
      
    case 'tokens':
      $type = $arg1;
      $tokens = array();
      // These are the token groups that will be used for this module's messages
      $tokens = array('global','user','node');
      return $tokens;
  }
}