You're right, he does highlight the distinction between people you know and people you should know. I instantly thought of Ark when hearing about this. I'd like to see how they and Ark might facilitate those connections once you've identified them. If I'm traveling abroad and meet someone from the same small town, I don't know how inclined I'll be to message them. Not to mention, those messages in Facebook get lost in the "Others" section where I've heard countless stories of people discovering important messages months later.