LOL.. I love this thread. I get absolutely no satisfaction out of idle chit chat about stupid stuff when it's with people I don't relate to. sometimes it's all part of "playing the game" to get through the day.. I think there is definitely a level of just manners and mutual respect you must have with coworkers if you want to get things done effectively... Not everyone understands, however, that everyone indeed does NOT have any interest in their grandkids pictures or how they are dealing with their irritable bowel syndrome. some people are trying to concentrate at their desks and don't want to listen to stupid BS. Unfortunately, at the same time, it might not be so effective to piss said person or persons off by telling them so, especially when they control how well you get the resources to complete your job. and chances might be good that if a person goes to lengths to talk about such things, they might go to lengths to retaliate if you express your disdane... That's the sucky part about people bringing their outside lives to work..
I say this because I've been there, done that, unfortunately, in previous job settings. It's just a matter of, as I said, playing the game of Work.
I will say it can be fun just bantering with someone I do relate to because I actually am interested in their opinion. I guess the deciding factor is just if I respect the person or not enough to care what they have to say. I am fortunate enough to work with people who are pretty cool, have interesting opinions, and can bring somethign to the table, so to speak. It might be luck of the draw though, because I work as an engineer and am surrounded by ENTJ's , INTJ's, ENTP's and INTP's. go figure...