Logan is correct. The true value of a press release is in its ability to have your cause, event, product, service or company recognized and disseminated through media outlets. A press release is most effective at driving targeted, interested traffic to your Web site. It brings your company's information and Web site to a mass audience likely previously unfamiliar with your company before.
The process of using press releases as a means to create backlinks to your site, for SEO, is valuable, but creating releases just for backlinks will warrant similar results to including your Web site link in your forum signature. Valuable, but nothing to write home about.
Good luck with your future marketing efforts!