When someone searches for you by name, Facebook results will often be one of the first they see. Google yourself to check. You want to make sure all results for your name will be viewed positively by hiring managers and recruiters. First you need to make sure you are aware that everything you do on Facebook could be seen by the whole world. That's why Facebook is more likely to cost you a job than find you one.
But you can turn that search result into a positive one. Employers know you are “off-duty” when you're on Facebook. Use Facebook to highlight an article relevant to your job every once in a while. Add technologies you use to your likes list. Join professional organizations that use Facebook. “Like” employers who influence you. All of these can help your job search.
Unfortunately you can't only include job-relevant information on your Facebook profile because you'd simply come off as fake. Besides, Facebook is primarily for connecting with friends. Just make sure the materials you're sharing remain employer-friendly.