Nginx: conditional "expires" directive

[somebi]

I'm getting:

Cache-Control:
Connection:keep-alive
Date:Tue, 16 Aug 2011 16:53:23 GMT
Last-Modified:Tue, 09 Aug 2011 05:32:58 GMT
Server:nginx

And 304 header

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,213841,213867#msg-213867