Facebook has built a page for reporting suicidal content that people see on the site. It's a form where you fill in the url where you spotted it, name of the person, time it was posted, what networks the person belongs to. The form also says that you should contact the police if you see that kind of language and it says that a Facebook official will review the content and take appropriate action. On Sunday, police found the body of a 12-year-old girl who had threatened on Facebook to kill herself. There was another high profile case in England recently.
What's kind of odd here is that if I hadn't read this article about the Facebook form, I never would have known it was there. It's not listed in any kind of obvious place. Can't search for it. In a situation like a threatened suicide, time matters a lot but there's nowhere to find the form and language that says "A Facebook administrator will review your report and take any available action from our end." is hardly a comfort.