SEO.com has a great post about using FAQ pages to help boost organic search. Apparently they've tested the technique and had good results. I've yet to try it out but it seems logical that it would work well for one very big reason: the average person creates search queries that are very similar in form to the questions on FAQ pages. This means their queries are likely to match with keywords and phrases on your FAQ page.
Using an FAQ page for SEO also gives you an opportunity to optimize for additional keywords that you haven't used in other areas of your site.
On the topic of search query formation, you should learn more about natural language search engines like Powerset. This is where many people believe search needs to evolve to.