Index: modules/node/node.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.pages.inc,v
retrieving revision 1.54
diff -u -r1.54 node.pages.inc
--- modules/node/node.pages.inc	5 Feb 2009 03:42:58 -0000	1.54
+++ modules/node/node.pages.inc	7 Feb 2009 22:09:02 -0000
@@ -247,6 +247,7 @@
     '#value' => t('Preview'),
     '#weight' => 10,
     '#submit' => array('node_form_build_preview'),
+    '#validate_section' => array('node_form_preview_validate_section'),
   );
   if (!empty($node->nid) && node_access('delete', $node)) {
     $form['buttons']['delete'] = array(
@@ -327,6 +328,13 @@
 }
 
 /**
+ * Validate section callback. Skip #required validation on preview.
+ */
+function node_form_preview_validate_section($form, $form_state) {
+  return array();
+}
+
+/**
  * Present a node submission form.
  *
  * @ingroup themeable