1. mkdir <myapp> && cd <myapp>
2. git clone git://github.com/Problematic/Symfony2Seed.git .
3. rm -rf .git
4. cp app/config/parameters.yml.dist app/config/parameters.yml
5. php bin/vendors install
6. git init
7. Begin work on your project with FOSUserBundle, Twitter Bootstrap, Underscore.js and Backbone.js already set to go for you

There was a Slashdot reference to be made in there, somewhere.