Adding extra information to the cart items & cart itself

Here in the Netherlands we have a extra fee on electronic products so that old products can be disposed of in an environmental friendly way called "verwijderingsbijdrage". these costs are added to the Ubercart module that i am using by a remote module, and i want to show these amounts in the cart itself.
i would like to propose implementing a hook that allows you to add extra information, and read this information in the template (i have commented on the lines where i made changes):

file uc_ajax_cart.theme.inc changes to functi on uc_ajax_cart_preprocess_uc_ajax_cart_block_content:

function uc_ajax_cart_preprocess_uc_ajax_cart_block_content(&$vars) {
  $content = $vars['items'];
  $items = array();

  $context = array(
    'revision' => 'themed',
    'type' => 'price',
  );

  $total = 0;
  $total_items = 0;
  foreach ($content as $item) {
    $display_item = module_invoke($item->module, 'cart_display', $item);
    if (!empty($display_item)) {
          $attributes = $item->data['attributes'];
          $total += $display_item['#total'];
          $total_items += $display_item['qty']['#default_value'];
            $items[] = array(
              'nid'      => $display_item['nid']['#value'],
              'qty'      => t('@qty×', array('@qty' => $display_item['qty']['#default_value'])),
              'title'    => $display_item['title']['#value'],
              'descr'    => isset($display_item['description']['#value']) ? $display_item['description']['#value'] : FALSE,
              'link'     => url('node/' . $item->nid),
              'item'     => $item,
              'image'    => uc_product_get_picture($display_item['nid']['#value'], 'cart'),
              'node'     => node_load($item->nid),
              'total'    => uc_price($display_item['#total'], array(
                'revision' => 'themed-original',
                'type' => 'amount',
              )),
              'extra_info' => array(),  //BEGIN alteration Jasper Pasman 2011-06-22 
              'remove_link' => l(t('Remove product'),
                                  UC_AJAX_CART_REMOVE_CALLBACK,
                                  array(
                                  'attributes' => array(
                                                    'onclick' => "ajaxCartBlockUIRemove(this.href); return false;",
                                                    'class'    => 'remove-cart-link remove-cart-link-' . $display_item['nid']['#value'],
                                                  ),
                                  'query' => array(
                                    'nid' => $display_item['nid']['#value'],
                                    'destination' => $_GET['q'],
                                    'data' => base64_encode($display_item['data']['#value']),
                                    'action' => 'remove',
                                  ),
                                )
                              ),
            );
    }
  }
  //$vars['total'] = uc_price($total, $context);alteration Jasper Pasman: theming of info needs to be done after the hook implementation
  $vars['total'] = $total;  // alteration Jasper Pasman 2011-06-22
  $vars['items'] = $items;
  $vars['item_count'] = $total_items;
  $vars['cart_links'] = theme('uc_ajax_cart_cart_links');
  $vars['items_text'] = format_plural( $total_items , '<span class="num-items">@count</span> Item', '<span class="num-items">@count</span> Items');
  $vars['extra_info'] = array(); //alteration Jasper Pasman 2011-06-22    

  // Invoke hook_ajax_cart_block_content()
  foreach (module_list() as $module) {      
    $func = $module .'_ajax_cart_block_content';
    if (function_exists($func)) { 
        $func($vars);
    }
  }  
  $vars['total'] = uc_price($vars['total'], $context); 

}

changes to file templates/uc_ajax_cart_block_content.tpl.php:

// $Id: uc_ajax_cart_block_content.tpl.php,v 1.1.2.6 2010/05/01 12:42:30 erikseifert Exp $
/**
 * @file
 *
 * Theme file for non empty cart.
 */
?>
<div id="cart-block-contents-ajax">
  <table class="cart-block-items">
    <thead>
      <tr>
        <th colspan="4">
          <?php print t('Products')?>
        </th>
      </tr>
    </thead>
    <tbody>
      <?php foreach ( $items as $item ):?>
      <tr class="odd">
        <td class="cart-block-item-qty">
          <?php print $item['qty'] ?>
        </td>
        <td class="cart-block-item-title">
          <a title="<?php print check_plain($item['descr']); ?>" href="<?php print $item['link'] ?>"><?php print $item['title'] ?><?php print $item['descr'] ?></a>
        </td>
        <td>
          <?php print $item['total'] ?>
        </td>
        <td></td>
      </tr>
      <?php
        // alteration Jasper Pasman 2011-06-22: begin showing item's extra information
        foreach($item['extra_info'] as $extra_info_key => $extra_info_record) {
      ?>
      <tr class="odd">
        <td colspan="4" class="cart-block-item-title">
            <?php print $extra_info_record; ?>
        </td>
      </tr>
      <?php 
        } //END alteration Jasper Pasman 2011-06-22 
      ?>
    <tr class="odd">
        <td colspan="4" class="cart-block-item-desc">
          <?php print $item['remove_link'] ?>
        </td>
      </tr>
      <?php endforeach; ?>
    </tbody>
  </table>
</div>
<table>
  <tbody>
    <?php                                                                                                                                                               
      // alteration Jasper Pasman 2011-06-22: begin showing item's extra information                                                                                    
      foreach($extra_info as $extra_info_key => $extra_info_record) {                                                                                           
    ?>                                                                                                                                                                  
    <tr class="odd">                                                                                                                                                    
      <td colspan="4" class="cart-block-item-title">                                                                                                                    
          <?php print $extra_info_record; ?>                                                                                                                            
      </td>                                                                                                                                                             
    </tr>                                                                                                                                                               
    <?php                                                                                                                                                               
      } //END alteration Jasper Pasman 2011-06-22                                                                                                                       
    ?>  
    <tr>
      <td class="cart-block-summary-items">
        <?php print $items_text; ?>
      </td>
      <td class="cart-block-summary-total">
        <label><?php print t('Total'); ?>: </label><?php print $total ;?>
      </td>
    </tr>
    <tr class="cart-block-summary-links">
      <td colspan="2">
        <?php print $cart_links; ?>
      </td>
    </tr>
  </tbody>
</table>

implementation example of the hook:

/**
 * Implementation of hook_ajax_cart_block_content
 */
function MYMODULE_ajax_cart_block_content(&$vars){
    $verwijderingsbijdrage = 0; 
    $context = array(                                                                                                                                                             'revision' => 'themed',                                                                                                                                                   'type' => 'price',                                                                                                                                                
    ); 
    foreach($vars['items'] as $item_index => $item){
        $item_verwijderingsbijdrage = 1; // i use a personal function here ica_uc_verwijderingsbijdrage_product_get_verwijderingsbijdrage($item['node']->model, $item['qty']); but for the testing code here i have coimmented it, but it shows the idea
        $verwijderingsbijdrage_total = $verwijderingsbijdrage + $item_verwijderingsbijdrage;                                                                                   
        $vars['items'][$item_index]['extra_info'][] = t('verwijderingsbijdrage') .': ' .  uc_price($item_verwijderingsbijdrage, $context);
    }
    $vars['total'] = $vars['total'] + $verwijderingsbijdrage_total;
    $vars['extra_info'][] = '<label>' . t('Total') . ' '. t('verwijderingsbijdrage') . ': </label>' . uc_price($verwijderingsbijdrage_total, $context); 
}

it seems a very usefull function to me and i would love to see it implemented.