There has been much more anecdotal discussion of this idea than actual research. There is the general understanding that if we get people to talk to one another more, they will tend to talk about their common interests, from sports to the day's topics at work.

It's not all anecdote. Community of practice researchers have shown the power of having people talk to one another. There is also a long discussion of loose connections vs. strong connections and the power of technology to help us make many more loose ties with people, such as this email, over a loose interest link. Mathamegenic has a recent discussion: http://blog.mathemagenic.com/2003/11/23.html#a849.