Index: wp-includes/template-functions-post.php
===================================================================
--- wp-includes/template-functions-post.php	(revision 3469)
+++ wp-includes/template-functions-post.php	(working copy)
@@ -258,9 +258,11 @@
 	if ( $keys = get_post_custom_keys() ) {
 		echo "<ul class='post-meta'>\n";
 		foreach ( $keys as $key ) {
-			$values = array_map('trim',$post_meta_cache[$id][$key]);
-			$value = implode($values,', ');
-			echo "<li><span class='post-meta-key'>$key:</span> $value</li>\n";
+			if (0 !== strpos(trim($key), '_')) {
+				$values = array_map('trim',$post_meta_cache[$id][$key]);
+				$value = implode($values,', ');
+				echo "<li><span class='post-meta-key'>$key:</span> $value</li>\n";
+			}
 		}
 		echo "</ul>\n";
 	}