Index: default-widgets.php
===================================================================
--- default-widgets.php	(revision 14093)
+++ default-widgets.php	(working copy)
@@ -424,6 +424,8 @@
 	}
 
 	function widget( $args, $instance ) {
+		static $widget_number = 0;
+		$widget_number++;
 		extract( $args );
 
 		$title = apply_filters('widget_title', empty( $instance['title'] ) ? __( 'Categories' ) : $instance['title'], $instance, $this->id_base);
@@ -439,18 +441,19 @@
 
 		if ( $d ) {
 			$cat_args['show_option_none'] = __('Select Category');
-			wp_dropdown_categories(apply_filters('widget_categories_dropdown_args', $cat_args));
+			$dropdown_name = $cat_args['name'] = 'category_jumpmenu' . $widget_number;
+			wp_dropdown_categories( apply_filters( 'widget_categories_dropdown_args' , $cat_args ) );
 ?>
 
 <script type='text/javascript'>
 /* <![CDATA[ */
-	var dropdown = document.getElementById("cat");
-	function onCatChange() {
-		if ( dropdown.options[dropdown.selectedIndex].value > 0 ) {
-			location.href = "<?php echo home_url(); ?>/?cat="+dropdown.options[dropdown.selectedIndex].value;
+	var dropdown<?php echo $widget_number; ?> = document.getElementById("<?php echo $dropdown_name; ?>");
+	function on<?php echo $dropdown_name; ?>Change() {
+		if ( dropdown<?php echo $widget_number; ?>.options[dropdown<?php echo $widget_number; ?>.selectedIndex].value > 0 ) {
+			location.href = "<?php echo home_url(); ?>/?cat="+dropdown<?php echo $widget_number; ?>.options[dropdown<?php echo $widget_number; ?>.selectedIndex].value;
 		}
 	}
-	dropdown.onchange = onCatChange;
+	dropdown<?php echo $widget_number; ?>.onchange = on<?php echo $dropdown_name; ?>Change;
 /* ]]> */
 </script>