This is a great question, and I'm sure you are fully aware that the solution is going to be specific to the situation.
Ironically, my most disruptive classes are the over-full honors classes, and at that, most often only 9th and 10th graders. These are students who have never had to work hard to make A's. Why should they think my class would be any different? In such a class, you would have done best to just sit down and be quiet when the rest of the class was talking. Trust me, you teacher notices, and loves you for it. Sadly, these classes are most often "punished" with more homework, more quizzes, more formal assessment, because there is such a lack of subject-focused discussion.
In other situations, I think it very highly depends on your relationship with the disruptors. I also agree that it is the teacher's job to maintain control, but once in a while, a student has the ability to diffuse a disruptive situation better than a teacher. Role modeling good behavior goes a long way, and this doesn't mean being the kid who sits at the front and answers all the questions. It seems being "smart" isn't exactly popular in most public high schools, but it could be, if, like Pohnpei said, enough "cool" kids were doing it.