The most common form of force feedback in our electronic devices is the sort of rumbling buzz you get when a motor spins some sort of mass inside the case of your hardware. Video game controllers usually have two motors, one on each side of the controller, and that sort of "rumble in stereo" configuration allows for a number of effects based on the speed of each motor. This takes power, it takes space, and there's not much you can do with the technology. At CES I met with Artificial Muscle, a Bayer MaterialScience company, so they could show me their Vivitouch technology. Vivitouch a sort of artificial muscle that could changing how we experience haptic effects in our devices.
A big part of the engineering of robotic exoskeleton devices like the HULC man magnifier and things like surgical robots is 'Haptics'. It will be a part of the Man Bird too.