On the symfony blog there's a recent post looking at a new bit of functionality in the 1.3 series of the framework - the ability to customize some things about project creation.
As you might know, symfony tasks are classes. As any other class, it is pretty easy to customize and extend the existing tasks; except for one of them: the generate:project task. That's because no project exists when you execute this task, and so there is no way to customize it... until now.
Previously, when generating a project, you were limited in the control of how things were set up. With this new feature you can define (via an --installer option) a configuration script that gives you several new methods to call: installDir, runTask, logging tools, filesystem operations and, of course, any other standard PHP functionality (since it's just a PHP script, after all).