wordpress.com is doing it right

[root@unitedgamesfactory /]# curl -I wordpress.com
HTTP/1.1 200 OK
Server: nginx
Date: Mon, 04 Jul 2011 22:32:02 GMT
Content-Type: text/html; charset=UTF-8
Connection: close
Vary: Accept-Encoding
Last-Modified: Mon, 04 Jul 2011 22:27:25 +0000
Cache-Control: max-age=23, must-revalidate
Vary: Cookie
Set-Cookie: hiab=off; path=/; domain=.wordpress.com
X-hacker: If you’re reading this, you should visit automattic.com/jobs and apply to join the fun, mention this header.
X-Pingback: http://wordpress.com/xmlrpc.php
Link: ; rel=shortlink
X-nananana: Batcache