$this->set('validationErrors', $errors);

$GLOBALS['validationErrors'] = $errors;

<?php if (isset($GLOBALS['validationErrors'])) {
    echo 'The following problems were found:<ul>';
    foreach($GLOBALS['validationErrors'] as $error) {
        echo '<li>'.$error.'</li>'
    }
    echo '</ul>';
} ?>

<?php
if(is_array($arrErrors) && count($arrErrors) > 0){
   $this->controller->setErrors($arrErrors);
}else{
   // display as normal
}
?>

<?php
protected $errors = array();
public function setErrors($arr){
   $this->errors = is_array($arr) ? $arr : array();
}
public function getErrors(){
   return is_array($this->errors) && count($this->errors) > 0) $this->errors ? FALSE;
}
?>

<?php
// NOTE: This would be while not in edit mode otherwise you couldn't edit the area's blocks
$area = new Area('Main content');
$arrBlocks = $area->getAreaBlocksArray($c);
foreach($arrBlocks as $b){
   if($b->getBlockTypeHandle() == 'my_block_handle'){   
      ob_start();
      $b->display('view', $args = array());
      $htmContent = ob_get_clean();
      $bc = $b->getController();
      if($arrErrors = $bc->getErrors()){
         // Iterate through the errors
      }else{
         // No errors so good to go
         echo $htmContent;

Events::extend(
   'on_before_render',
   'ValidationMessages',
   'setValidationMessages',
   'models/validation_messages.php',
   array( $errors )
);

class ValidationMessages {
   public function setValidationMessages( $v, $msgs ) {
      $v->controller->set('validationMessages',$msgs);
   }
}

extract($this->controller->getSets());

if (isset($validationMessages)) {
   foreach ($validationMessages as $validationMessage) {
      echo '<p>'.$validationMessage.'</p>';
   }
}