Index: wp-includes/pluggable.php
===================================================================
--- wp-includes/pluggable.php	(revision 20951)
+++ wp-includes/pluggable.php	(working copy)
@@ -831,8 +831,10 @@
  *
  * @param string $action Action nonce
  * @param string $query_arg where to look for nonce in $_REQUEST (since 2.5)
+ * @param bool $die Die if checking fails
+ * @param bool $renonce If checking succeeds, calculate a new nonce and send it as an X-WP-nonce header
  */
-function check_ajax_referer( $action = -1, $query_arg = false, $die = true ) {
+function check_ajax_referer( $action = -1, $query_arg = false, $die = true, $renonce = false ) {
 	if ( $query_arg )
 		$nonce = $_REQUEST[$query_arg];
 	else
@@ -849,6 +851,9 @@
 
 	do_action('check_ajax_referer', $action, $result);
 
+	if ( $renonce && !headers_sent() )
+		header( 'X-WP-nonce: ' . $action . '=' . wp_create_nonce( $action ) );
+	
 	return $result;
 }
 endif;
Index: wp-includes/script-loader.php
===================================================================
--- wp-includes/script-loader.php	(revision 20951)
+++ wp-includes/script-loader.php	(working copy)
@@ -373,6 +373,9 @@
 		$scripts->add( 'admin-gallery', "/wp-admin/js/gallery$suffix.js", array( 'jquery-ui-sortable' ) );
 
 		$scripts->add( 'admin-widgets', "/wp-admin/js/widgets$suffix.js", array( 'jquery-ui-sortable', 'jquery-ui-draggable', 'jquery-ui-droppable' ), false, 1 );
+		$scripts->localize( 'admin-widgets', 'widgetsL10n', array(
+			'loggedOut' => __('You are logged out!')
+		));
 
 		$scripts->add( 'theme', "/wp-admin/js/theme$suffix.js", array( 'jquery' ), false, 1 );
 
Index: wp-admin/includes/ajax-actions.php
===================================================================
--- wp-admin/includes/ajax-actions.php	(revision 20951)
+++ wp-admin/includes/ajax-actions.php	(working copy)
@@ -1510,7 +1510,7 @@
 }
 
 function wp_ajax_widgets_order() {
-	check_ajax_referer( 'save-sidebar-widgets', 'savewidgets' );
+	check_ajax_referer( 'save-sidebar-widgets', 'savewidgets', true, true );
 
 	if ( !current_user_can('edit_theme_options') )
 		wp_die( -1 );
@@ -1543,7 +1543,7 @@
 function wp_ajax_save_widget() {
 	global $wp_registered_widgets, $wp_registered_widget_controls, $wp_registered_widget_updates;
 
-	check_ajax_referer( 'save-sidebar-widgets', 'savewidgets' );
+	check_ajax_referer( 'save-sidebar-widgets', 'savewidgets', true, true );
 
 	if ( !current_user_can('edit_theme_options') || !isset($_POST['id_base']) )
 		wp_die( -1 );
Index: wp-admin/js/widgets.dev.js
===================================================================
--- wp-admin/js/widgets.dev.js	(revision 20951)
+++ wp-admin/js/widgets.dev.js	(working copy)
@@ -189,8 +189,11 @@
 				a['sidebars[' + $(this).attr('id') + ']'] = $(this).sortable('toArray').join(',');
 		});
 
-		$.post( ajaxurl, a, function() {
+		var xhr = $.post( ajaxurl, a, function() {
 			$('img.ajax-feedback').css('visibility', 'hidden');
+			nonce_header = xhr.getResponseHeader("X-WP-nonce");
+			nonce = nonce_header.split("=", 2)[1];
+			$('#_wpnonce_widgets').val(nonce);
 		});
 
 		this.resize();
@@ -212,9 +215,19 @@
 
 		data += '&' + $.param(a);
 
-		$.post( ajaxurl, data, function(r){
+		var xhr = $.post( ajaxurl, data, function(r){
 			var id;
 
+			if ( "0" === r ) {
+				logout_message = $('.logout-message', widget)
+				if ( !logout_message.length ) {
+					$('img.ajax-feedback', widget).parent().parent().append($('<div class="error logout-message"><p>' + widgetsL10n.loggedOut + '</p></div>'));
+				}
+				$('.ajax-feedback', widget).css('visibility', 'hidden');
+				logout_message.fadeOut(50).fadeIn(500);
+				return false;
+			}
+
 			if ( del ) {
 				if ( !$('input.widget_number', widget).val() ) {
 					id = $('input.widget-id', widget).val();
@@ -236,14 +249,20 @@
 				}
 			} else {
 				$('.ajax-feedback').css('visibility', 'hidden');
+				$('.logout-message', widget).hide();
 				if ( r && r.length > 2 ) {
 					$('div.widget-content', widget).html(r);
 					wpWidgets.appendTitle(widget);
 					wpWidgets.fixLabels(widget);
 				}
 			}
-			if ( order )
+			if ( order ) {
 				wpWidgets.saveOrder();
+			} else {
+				nonce_header = xhr.getResponseHeader("X-WP-nonce");
+				nonce = nonce_header.split("=", 2)[1];
+				$('#_wpnonce_widgets').val(nonce);
+			}
 		});
 	},
 
Index: wp-admin/css/wp-admin.dev.css
===================================================================
--- wp-admin/css/wp-admin.dev.css	(revision 20951)
+++ wp-admin/css/wp-admin.dev.css	(working copy)
@@ -7883,7 +7883,7 @@
 	display: block;
 }
 
-.widget .widget-inside p {
+.widget-inside p {
 	margin: 0 0 1em;
 	padding: 0;
 }