It wouldn't surprise me if Facebook created profiles for people who've never used it, just by virtue of having enough of their friends having their contact details. IE if 5 people are friends and all have "fred bloggs" in their contact list then there's a good chance it's the same "fred bloggs". I'm not sure what this virtual person is worth to advertisers, though, just like I'm not sure what you're worth if you don't use it any more.