Index: wp-includes/taxonomy.php
===================================================================
--- wp-includes/taxonomy.php	(revision 10242)
+++ wp-includes/taxonomy.php	(working copy)
@@ -534,6 +534,10 @@
  * of term ids to exclude from the return array.  If 'include' is non-empty,
  * 'exclude' is ignored.
  *
+ * exclude_tree - A comma- or space-delimited string of term ids to exclude
+ * from the return array, along with all of their descendant terms according to 
+ * the primary taxonomy.  If 'include' is non-empty, 'exclude_tree' is ignored.
+ *
  * include - Default is an empty string.  A comma- or space-delimited string
  * of term ids to include in the return array.
  *
@@ -604,7 +608,7 @@
 	$in_taxonomies = "'" . implode("', '", $taxonomies) . "'";
 
 	$defaults = array('orderby' => 'name', 'order' => 'ASC',
-		'hide_empty' => true, 'exclude' => '', 'include' => '',
+		'hide_empty' => true, 'exclude' => '', 'exclude_tree' => '', 'include' => '',
 		'number' => '', 'fields' => 'all', 'slug' => '', 'parent' => '',
 		'hierarchical' => true, 'child_of' => 0, 'get' => '', 'name__like' => '',
 		'pad_counts' => false, 'offset' => '', 'search' => '');
@@ -668,6 +672,7 @@
 	$inclusions = '';
 	if ( !empty($include) ) {
 		$exclude = '';
+		$exclude_tree = '';
 		$interms = preg_split('/[\s,]+/',$include);
 		if ( count($interms) ) {
 			foreach ( (array) $interms as $interm ) {
@@ -684,11 +689,25 @@
 	$where .= $inclusions;
 
 	$exclusions = '';
+	if ( ! empty( $exclude_tree ) ) {
+		$excluded_trunks = preg_split('/[\s,]+/',$exclude_tree);
+		foreach( (array) $excluded_trunks as $extrunk ) {
+			$excluded_children = (array) get_terms($taxonomies[0], array('child_of' => intval($extrunk), 'fields' => 'ids'));	
+			$excluded_children[] = $extrunk;
+			foreach( (array) $excluded_children as $exterm ) {
+				if ( empty($exclusions) )
+					$exclusions = ' AND ( t.term_id <> ' . intval($exterm) . ' ';
+				else
+					$exclusions .= ' AND t.term_id <> ' . intval($exterm) . ' ';
+
+			}
+		}
+	}
 	if ( !empty($exclude) ) {
 		$exterms = preg_split('/[\s,]+/',$exclude);
 		if ( count($exterms) ) {
 			foreach ( (array) $exterms as $exterm ) {
-				if (empty($exclusions))
+				if ( empty($exclusions) )
 					$exclusions = ' AND ( t.term_id <> ' . intval($exterm) . ' ';
 				else
 					$exclusions .= ' AND t.term_id <> ' . intval($exterm) . ' ';
Index: wp-includes/category-template.php
===================================================================
--- wp-includes/category-template.php	(revision 10242)
+++ wp-includes/category-template.php	(working copy)
@@ -443,6 +445,7 @@
  *     'feed_image' - See {@link get_categories()}.
  *     'child_of' (int) default is 0 - See {@link get_categories()}.
  *     'exclude' (string) - See {@link get_categories()}.
+ *     'exclude_tree' (string) - See {@link get_categories()}.
  *     'echo' (bool|int) default is 1 - Whether to display or retrieve content.
  *     'current_category' (int) - See {@link get_categories()}.
  *     'hierarchical' (bool) - See {@link get_categories()}.
@@ -461,7 +464,7 @@
 		'style' => 'list', 'show_count' => 0,
 		'hide_empty' => 1, 'use_desc_for_title' => 1,
 		'child_of' => 0, 'feed' => '', 'feed_type' => '',
-		'feed_image' => '', 'exclude' => '', 'current_category' => 0,
+		'feed_image' => '', 'exclude' => '', 'exclude_tree' => '', 'current_category' => 0,
 		'hierarchical' => true, 'title_li' => __( 'Categories' ),
 		'echo' => 1, 'depth' => 0
 	);