Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 8621)
+++ wp-includes/post.php	(working copy)
@@ -1369,8 +1369,10 @@
 	}
 
 	if ( $update || '0000-00-00 00:00:00' == $post_date ) {
-		$post_modified     = current_time( 'mysql' );
-		$post_modified_gmt = current_time( 'mysql', 1 );
+		if(apply_filters('update_modified',true,$postarr)) {
+			$post_modified     = current_time( 'mysql' );
+			$post_modified_gmt = current_time( 'mysql', 1 );
+		}
 	} else {
 		$post_modified     = $post_date;
 		$post_modified_gmt = $post_date_gmt;
Index: wp-admin/edit-form-advanced.php
===================================================================
--- wp-admin/edit-form-advanced.php	(revision 8621)
+++ wp-admin/edit-form-advanced.php	(working copy)
@@ -154,6 +154,7 @@
 </div>
 
 <p class="submit">
+<?php do_action('editpost_presave',$post) ?>
 <input type="submit" name="save" id="save-post" value="<?php _e('Save'); ?>" tabindex="4" class="button button-highlighted" />
 <?php
 if ( !in_array( $post->post_status, array('publish', 'future') ) || 0 == $post_ID ) {