Index: wp-admin/includes/post.php
===================================================================
--- wp-admin/includes/post.php	(revision 24075)
+++ wp-admin/includes/post.php	(working copy)
@@ -1212,15 +1212,12 @@
 	<?php
 
 	if ( $locked ) {
-		$preview_link = set_url_scheme( add_query_arg( 'preview', 'true', get_permalink( $post->ID ) ) );
+		$preview_args = array( 'preview' => 'true' );
 
-		if ( 'publish' == $post->post_status || $user->ID != $post->post_author ) {
-			// Latest content is in autosave
-			$nonce = wp_create_nonce( 'post_preview_' . $post->ID );
-			$preview_link = add_query_arg( array( 'preview_id' => $post->ID, 'preview_nonce' => $nonce ), $preview_link );
-		}
+		if ( 'publish' == $post->post_status || $user->ID != $post->post_author ) // Latest content is in autosave
+			$preview_args['latest_changes'] = 'true';
 
-		$preview_link = apply_filters( 'preview_post_link', $preview_link );
+		$preview_link = apply_filters( 'preview_post_link', add_query_arg( $preview_args, get_permalink( $post->ID ) ) );
 		$override = apply_filters( 'override_post_lock', true, $post, $user );
 		$tab_last = $override ? '' : ' wp-tab-last';
 
@@ -1366,23 +1363,20 @@
 	}
 
 	$user_id = get_current_user_id();
+	$query_args = array( 'preview' => 'true' );
+
 	if ( 'draft' == $post->post_status && $user_id == $post->post_author ) {
 		$id = edit_post();
 	} else { // Non drafts are not overwritten. The autosave is stored in a special post revision.
 		$id = wp_create_post_autosave( $post->ID );
-		if ( ! is_wp_error($id) )
+		if ( ! is_wp_error($id) ) {
 			$id = $post->ID;
+			$query_args['latest_changes'] = 'true';
+		}
 	}
 
 	if ( is_wp_error($id) )
 		wp_die( $id->get_error_message() );
 
-	if ( $_POST['post_status'] == 'draft' && $user_id == $post->post_author ) {
-		$url = add_query_arg( 'preview', 'true', get_permalink($id) );
-	} else {
-		$nonce = wp_create_nonce('post_preview_' . $id);
-		$url = add_query_arg( array( 'preview' => 'true', 'preview_id' => $id, 'preview_nonce' => $nonce ), get_permalink($id) );
-	}
-
-	return apply_filters( 'preview_post_link', $url );
+	return apply_filters( 'preview_post_link', add_query_arg( $query_args, get_permalink($id) ) );
 }
Index: wp-includes/default-filters.php
===================================================================
--- wp-includes/default-filters.php	(revision 24075)
+++ wp-includes/default-filters.php	(working copy)
@@ -277,8 +277,9 @@
 add_action( 'template_redirect', 'wp_old_slug_redirect'              );
 add_action( 'post_updated',      'wp_check_for_changed_slugs', 12, 3 );
 
-// Nonce check for Post Previews
-add_action( 'init', '_show_post_preview' );
+// Post Previews
+add_filter( 'the_preview', '_set_preview' );
+add_filter( 'preview_post_link', '_wp_add_preview_nonce', 5 );
 
 // Timezone
 add_filter( 'pre_option_gmt_offset','wp_timezone_override_offset' );
Index: wp-includes/query.php
===================================================================
--- wp-includes/query.php	(revision 24075)
+++ wp-includes/query.php	(working copy)
@@ -2732,8 +2732,12 @@
 				}
 			}
 
-			if ( $this->is_preview && $this->posts && current_user_can( $edit_cap, $this->posts[0]->ID ) )
-				$this->posts[0] = get_post( apply_filters_ref_array( 'the_preview', array( $this->posts[0], &$this ) ) );
+			if ( $this->is_preview && $this->posts && current_user_can( $edit_cap, $this->posts[0]->ID ) ) {
+				if ( $the_preview = apply_filters( 'the_preview', $this->posts[0], $this ) )
+					$this->posts[0] = get_post( $the_preview );
+				else
+					$this->posts = array();
+			}
 		}
 
 		// Put sticky posts at the top of the posts array
Index: wp-includes/revision.php
===================================================================
--- wp-includes/revision.php	(revision 24075)
+++ wp-includes/revision.php	(working copy)
@@ -496,40 +496,39 @@
 	return (int) apply_filters( 'wp_revisions_to_keep', $num, $post );
 }
 
-function _set_preview($post) {
+/**
+ * Check the nonce for preview links. Overload the content
+ * wiht the latest autosave when 'latest_changes' is set.
+ *
+ * @access private
+ */
+function _set_preview( $post ) {
+	// Don't show a preview if the user is not coming from a 'preview' link in the admin
+	if ( empty( $_GET['preview_nonce'] ) || ! wp_verify_nonce( $_GET['preview_nonce'], 'post-preview' ) )
+		return false;
 
-	if ( ! is_object($post) )
-		return $post;
+	if ( isset($_GET['latest_changes']) ) {
+		if ( ! is_object($post) )
+			return $post;
 
-	$preview = wp_get_post_autosave($post->ID);
+		$preview = wp_get_post_autosave( $post->ID );
 
-	if ( ! is_object($preview) )
-		return $post;
+		if ( ! is_object($preview) )
+			return $post;
 
-	$preview = sanitize_post($preview);
+		$preview = sanitize_post($preview);
 
-	$post->post_content = $preview->post_content;
-	$post->post_title = $preview->post_title;
-	$post->post_excerpt = $preview->post_excerpt;
+		$post->post_content = $preview->post_content;
+		$post->post_title = $preview->post_title;
+		$post->post_excerpt = $preview->post_excerpt;
 
-	add_filter( 'get_post_metadata', '_wp_preview_meta_filter', 10, 4 );
-	add_filter( 'get_the_terms', '_wp_preview_terms_filter', 10, 3 );
+		add_filter( 'get_post_metadata', '_wp_preview_meta_filter', 10, 4 );
+		add_filter( 'get_the_terms', '_wp_preview_terms_filter', 10, 3 );
+	}
 
 	return $post;
 }
 
-function _show_post_preview() {
-
-	if ( isset($_GET['preview_id']) && isset($_GET['preview_nonce']) ) {
-		$id = (int) $_GET['preview_id'];
-
-		if ( false == wp_verify_nonce( $_GET['preview_nonce'], 'post_preview_' . $id ) )
-			wp_die( __('You do not have permission to preview drafts.') );
-
-		add_filter('the_preview', '_set_preview');
-	}
-}
-
 /**
  * Filters post meta retrieval to get values from the actual autosave post,
  * and not its parent. Filters revisioned meta keys only.
@@ -573,6 +572,21 @@
 	return $terms;
 }
 
+/**
+ * Add a nonce to all preview links.
+ *
+ * @since 3.6.0
+ * @access private
+ */
+function _wp_add_preview_nonce( $url )  {
+	static $nonce;
+
+	if ( ! $nonce )
+		$nonce = wp_create_nonce('post-preview');
+
+	return add_query_arg( 'preview_nonce', $nonce, $url );
+}
+
 function _wp_get_post_revision_version( $revision ) {
 	if ( is_object( $revision ) )
 		$revision = get_object_vars( $revision );