Sub-domains only server for web application?

[anagio]

Our website currently runs wordpress to manage the front end site
www.example.com

When users register they get a subdomain username.example.com where they
can login to our application. The application is built on zend
framework. I'd like to have the zf project on an entirely different
server than where we run the wordpress www.example.com domain.

How would the default server config be setup since the front end site is
on another server with different IP? Virtual hosts would be setup as
usual, i'm just not sure how to configure the main server so it
redirects to www.example.com? Any help is appreciated

Thanks

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,218630,218630#msg-218630