If anyone wants to install  and try Phusion Passenger (an application server for Ruby, Python and Node.js) with Apache ( aka ModRails ), I would like to point out this nice guide :

http://www.modrails.com/documentation/Users%20guide%20Apache.html#install_on_debian_ubuntu

The only thing I changed is where the guide says to protect the user created file “passenger.list” with chmod 600.Since this was throwing an error in my system, I changed the permissions to 644 and that’s it!

Enjoy!