Index: wp-includes/shortcodes.php
===================================================================
--- wp-includes/shortcodes.php	(revision 13945)
+++ wp-includes/shortcodes.php	(working copy)
@@ -293,6 +293,21 @@
 	return preg_replace('/'.$pattern.'/s', '$1$6', $content);
 }
 
+/**
+ * Clean up any 'escaped' brackets for unavailable shortcodes.
+ *
+ * @since 3.0
+ *
+ * @param string $content Content to clean up.
+ * @return string Content with single square brackets for unavailable shortcodes.
+ */
+function clean_shortcodes( $content ) {
+	$pattern = '\[(\[.*?\])\]';
+
+	return preg_replace( '/'.$pattern.'/s', '$1', $content );
+}
+
 add_filter('the_content', 'do_shortcode', 11); // AFTER wpautop()
+add_filter('the_content', 'clean_shortcodes', 12); // after applying shortcodes
 
-?>
\ No newline at end of file
+?>