There have been a few times when the people around me were talking louder than I would have perfered. But never quite to the point that I felt the need to ask them to talk a little quieter. Typically after a bit they have talked themsleves silly and quieted down.

But being the the person I am if it had gotten to that point I would have probably gotten up from my seat and found a flight attendent and requested that they ask people in seats such and such to talk a bit quieter. I bet having the flight attendendent do this would get the job done without pissing anyone off.