On NetTuts.com there's a recent tutorial posted that helps you "dive into Symfony2" and gives you an introduction to the framework including some code samples of a basic MVC structure.

Frameworks are hot topics in the web-industry and have been for some time. In this vast sea of flavors is Symfony – an extensive PHP framework that follows the ever popular MVC paradigm. Its learning curve is probably a little steeper than its fellow competitors, like CodeIgniter. Don’t worry, once it grows on you, you’ll feel more powerful than ever and you’ll be able to develop fantastic applications.

They walk you through a few different things including the overall flow of a Symfony2 application and getting it installed (and where its files live). They show you how to use the console commands to generate parts of an application and creating controllers/routes/output via Twig as well.