Gossip is talking about people who are not present without their permission; it does not have to be malicious. I've been thinking recently about whether one should avoid it altogether.
After all, if Abigail wants me to know something, she will tell me. And if Abigail wants Brenda to know her news, how much more fun for both to tell/hear it directly rather than have me steal Abigail's thunder.
Avoiding having a tightly-knit circle of friends whose one common interest is that they are a tightly-knit circle of friends is one good way of avoiding setting up a network of gossip. And instead maintaining friendships where one actually has common interests is another (getting the Civilisation board out rather than settling down with a cup of tea and "so do you know what X is doing now?", say).
However, we often come across stories or experiences that might help our friends. I used to think it is alright to say to someone worrying about possible infertility "Don't worry, I had a friend with polycystic ovaries and she got pregnant" as long as no names were mentioned and one came up with concrete ideas as well as anecdotal support ("have you read Taking Charge of your Fertility yet, Muriel?"). But I become less convinced of this as I realise how interconnected people with similar interests are (remember the Friends episode where Ross runs around trying to stop the trail?). I was once having a conversation with a friend of a friend who I had JUST MET and he said "Oh I was at a dinner party and X told this hilarious story about a woman who came into the shop where he works and she..." well, you don't need to know what she did that was so hilarious. She was me, of course. There's always a trail.
Of course, if something is out there in the public domain, then perhaps it makes no difference to pass it on further. But there is always the danger that one is the final step in the trail, like that hapless friend-of-a-friend of mine.
BTW, did you know that gossip is forbidden according to Jewish law?