How to change/add ports in apache2, in debian?

Question

My OS:
Linux version 2.6.26-2-xen-686 (Debian 2.6.26-25lenny1) ([email protected]) (gcc version 4.1.3 20080704 (prerelease) (Debian 4.1.2-25)) #1 SMP Fri Sep 17 00:54:08 UTC 2010

On my VPS, I need to use both php and ruby. So I want to use apache to handle my php sites and nginx for the ruby sites.
And pass the php request to apache through Nginx;
Then, I need to make apache bundle to another port except 80.

I have added 'Listen 8080' to /etc/ports.conf
and changed /etc/sites-enabled/000-default ( from [VirtualHost *:80] to [VirtualHost * : *])
and changed my virtual host ([VirtualHost * . *]);

Then restarted apache2

But when I request port 8080, it always direct me to the 80 port; I don't know why.
( Apache should not listen to 80 because I will make Nginx to listen to 80);

Any idea?