I never used to feel comfortable gossiping, but two people I live with are huge on gossiping (they are both istj, though murky). I now LOOOOOOVE gossip. Not so much knowing about other people's affairs, but just bitching about people in general. We have people who we have pretty much designated as 'bitch sinks', who take all our fire, and we can sit there for hours coming up with new ways to express just how much these people suck. I find it has made us infinitely closer, and provided endless hours of entertainment.
For those who need to know, it also clarifies just who is in the in-group and who is in the out-group. I guess it gives you an awareness of public perception before you decide to talk to someone, which is bad for the person involved, but can be good for you.
I dunno, I'm scraping the barrel here. I think it is generally against INTP nature to gossip, but it is fundamental to other personality types.