--- modules/field/field.module	2011-01-02 12:26:39.000000000 -0500
+++ modules/field/field_new.module	2011-01-09 16:23:59.721108104 -0500
@@ -1161,7 +1161,7 @@ function theme_field($variables) {
   // Render the items.
   $output .= '<div class="field-items"' . $variables['content_attributes'] . '>';
   foreach ($variables['items'] as $delta => $item) {
-    $classes = 'field-item ' . ($delta % 2 ? 'odd' : 'even');
+    $classes = 'field-item ' . ($delta % 2 ? 'odd' : 'even') . ($delta == 0 ? ' first' : '') . ($delta == count($delta) + 1 ? ' last' : '');
     $output .= '<div class="' . $classes . '"' . $variables['item_attributes'][$delta] . '>' . drupal_render($item) . '</div>';
   }
   $output .= '</div>';