If you rename one directory to another where the second directory exists as an empty directory it will not complain.
Not what I expected.
[pearcec@abe tmp]$ mkdir test1
[pearcec@abe tmp]$ mkdir test2
[pearcec@abe tmp]$ touch test1/test
[pearcec@abe tmp]$ php
<?php
rename("test1","test2");
?>
X-Powered-By: PHP/4.0.5
Content-type: text/html
[pearcec@abe tmp]$ ls -al
total 12
drwxr-xr-x 3 pearcec commnav 4096 Jun 15 13:17 .
drwxr-xr-x 18 pearcec commnav 4096 Jun 15 13:15 ..
drwxr-xr-x 2 pearcec commnav 4096 Jun 15 13:16 test2
[pearcec@abe tmp]$ ls -la test2/
total 8
drwxr-xr-x 2 pearcec commnav 4096 Jun 15 13:16 .
drwxr-xr-x 3 pearcec commnav 4096 Jun 15 13:17 ..
-rw-r--r-- 1 pearcec commnav 0 Jun 15 13:16 test
[pearcec@abe tmp]$
