You should always proxy the web server for your mogrels, processing a portion of static content and its compression. Requests for static content should never be passed to husbands.
eg. with nginx, it's just a matter of adding gzip directives to your configuration file.
http://topfunky.net/svn/shovel/nginx/conf/nginx.conf
# output compression saves bandwidth
gzip on;
gzip_http_version 1.0;
gzip_comp_level 2;
gzip_proxied any;
gzip_types text/plain text/html text/css application/x-javascript text/xml application/xml application/xml+rss text/javascript;