I'm wondering if the question was supposed to be "Does submitting your site to Free for All sites (such as Warrior forum, or this one I guess), make any difference to your rankings?" Well...there are thousands of users on this forum, Warrior forum and many others like it creating backlinks. As long it is part of an on and off page SEO strategy and is not your only strategy.
honestly though the juice you get from forums like those really doesn't add up to much unless your linked in to a load of them.....which i guess really is the idea in the end