I've been working on a rest API project for my company and one of the issues I had to work around with symfony2 is stateless authentication.
The built in security listeners in symfony2 all rely on cookies. Even when the stateless parameter is true in the security.yml, a cookie will be set.
If rest is to become a first class citizen in symfony2 I think the core should ship with a stateless friendly security listener.
For my project I've been using the LexikJWTAuthenticationBundle and to get around this issue I created this bundle:
https://github.com/gfreeau/GfreeauGetJWTBundle and it works great for my needs
which is a symfony2 based rest API for an angularjs frontend.