There is an anthropological book about how gossip is sort of a leftover trait from when we, as primates, groomed each other.
Yes, telling secrets about other people is the equivalent of sitting around, picking fleas out of each other's fur.
I think that when done in moderation, it helps people to feel more connected and closer to one another. Personally, if someone asks me specifically to not tell anyone else, I respect that. I do not say a WORD. However, if it's an observation that would help other people know more about a situation (say, a good friend is having a hard time but doesn't want to ask for help, but if everyone else knows then they can help her indirectly), then I think it's good.