The five-year-old social network will "memorialize" profiles of the dead if their friends or family request it. Such accounts will be different from regular Facebook profiles.
For example, the site will remove any contact information and bar people from logging in. The person's profile also won't appear in the "suggestions" section of Facebook, and only the deceased person's confirmed friends will be able to find them in a search.
I've already seen this phenomenon of memorialization play out in practice on Facebook, so I'm not surprised to see the practice formalized by the company. From my personal experience with a Facebook friend who died a few years ago, one part of me finds it very eerie - it was somewhat discomforting to see mutual friends continue to post on and interact with the profile years later at random intervals, creating the awkward protocol for such tributes as they went.
Another part of me, though, finds it interesting and possibly helpful (in the sense that the deceased person's page will always serve as a reminder and a crystallization of the individual). I suppose it's just a new, standard aspect of 'modern life.'