On the Knp Labs site there's a recent post showing you how to use Capifony (a tool designed for use with Symfony projects) to deploy your Symfony-based applications in a few easy steps.

Deploying should be an active part of your development process, but not something that gives you a headache. If deploying your entire application takes more than one command or doesn't put a smile on your face, you should keep reading. NOTE: This post will specifically cover how to deploy your Symfony2 application, but the library used here - capifony - is just as useful for deploying a symfony 1.x application.

He walks you through the simple five step process of installing and configuring the capifony tool to pull from a remote git repository, set up some shared directories and update the vendor libraries on deployment. A few more changes for the initial deployment and you'll be ready to call "cap deploy" any time you'd like to push the latest version of your application. He also points out that with version 2.0.9 and above of capifony, Doctrine database migrations are also supported. For more information on capifony, see the project's website.