Index: wp-content/themes/default/functions.php
===================================================================
--- wp-content/themes/default/functions.php	(revision 11001)
+++ wp-content/themes/default/functions.php	(working copy)
@@ -4,6 +4,18 @@
  * @subpackage Default_Theme
  */
 
+add_filter('manage_edit-comments_columns', 'wwww');
+function wwww($columns) {
+	$columns['yyy'] = "YYYY";
+	return $columns;
+}
+add_action('manage_comments_custom_column', 'xxxx', 10, 2);
+function xxxx($col_name, $comment_id) {
+	if ( $col_name == 'yyy' ) {
+		echo "id=$comment_id";
+	}
+}
+
 automatic_feed_links();
 
 if ( function_exists('register_sidebar') ) {
Index: wp-admin/includes/template.php
===================================================================
--- wp-admin/includes/template.php	(revision 11001)
+++ wp-admin/includes/template.php	(working copy)
@@ -2212,6 +2212,12 @@
 					echo "<a href='" . get_permalink( $post->ID ) . "'>#</a>";
 					echo '</div></td>';
 				}
+				break;
+			default:
+				echo "<td $attributes>\n";
+				do_action( 'manage_comments_custom_column', $column_name, $comment->comment_ID );
+				echo "</td>\n";
+				break;
 		}
 	}
 	echo "</tr>\n";