Dutch Roll and Yaw Damping
Dutch Roll mode frequency is typically less than 0.5 Hz. As a result, damping of the Dutch Roll mode provide on commercial transport aircraft by yaw dampers does not require particularly high bandwidth control. Early analog electronics of the first yaw damper modules provided quite adequate improvements in Dutch Roll damping. More recent designs have included more sophisticated control algorithms that provide higher fidelity turn coordination and higher bandwidth sideslip angle control, but the basic requirement to improve Dutch Roll mode damping is equally met by early model yaw dampers and the latest full authority directional augmentation control laws.
Taking another look at grounded27's entry, use of the word "flutter" jumps out at me. "Flutter" is a term reserved to describe unintended oscillation of either a control surface or airplane structure associated with lightly damped or unstable modes. To say that an airplane exhibits flutter is to suggest that it has a serious design or manufactoring flaw that would not be certifiable. To say that a control system is high bandwidth and results in rapid control surface motions is one thing. To characterize those motions as flutter is a completely different issue. Be careful with your choice of words.