ch.26 + 27: Not gossip exactly, in this case, but we can be sure the local grapevine is discussing it: Elizabeth's information to Mrs. Gardiner that Wickham has lost interest in her and is courting a certain Miss King, who has just come into 10,000 pounds
Ch.29: Wickham's accuracy in describing Lady Catherine is confirmed by her behaviour, despite Mr. and Mrs. Collins' assurances to the contrary.
Ch.29: Lady Catherine's information about the Miss Webbs, etc. would be of interest to anyone who actually knew them!
Ch.30: Wickham is also confirmed in saying that people generally expect Darcy and Anne to marry, given her mother's attitude.
Ch.33: Col. Fitzwilliam confides in Elizabeth what Darcy has done for a friend, whom he believes, but is not entirely sure, is Bingley.