This bundle helps you easily configure your feature toggling in Symfony2 by adding some simple tags to php twig and extending it's configuration.
It's under developement, and it's not usable at this moment.
You could add to your config.yml the following lines, but it won't work anyway:
feature_toggle:
features:
my_feature:
name: my_feature // the name you use in your template
enabled: true / false