Imagine this scenario: A user on your webpage finds an awesome link, but it's only open to registered users.
Normally our user will be redirected to login page and if they already have an account, they can login and get redirected to the page they were looking for. This is possible thanks to Symfony2 Authentication listener where a session parameter is set to what the last page was before firewall was hit and then purged the moment you login.
But what if they're a new user? After clicking another link to register and filling out the form, how can you redirect them back to the page they're actually looking for?