Engineering serendipity is this idea that we can help people come across unexpected but helpful connections at a better than random rate. And in some ways it's based on trying to reassess this notion of serendipitous as lucky - to think of serendipitous as smart.
It's my fond hope that social networks such as Facebook will help users broaden their perspectives by listening to a different set of people than they encounter in their daily life. But I fear services such as Facebook may be turning us into imaginary cosmopolitans.