Motion plus.. Its the wii addon that supposed to increase the sensitivity of the wii remote's gyroscopic angle. In other words, if the response of the tilt/angle ect of the controller isn't accurate or fast enough this should improve upon that without having to buy a whole new controller or console.
I'm not sure 100% of the specs, but i'm the guy who spent $ on buying the lightsaber sword sleeve, the blaster looking attachment, and driving wheel when all those items were nothing more than molded plastic that the controller sits into
Hopefully this will usher in some really solid sword based games. There's hasn't really been any really good Samurai style RPG games with a real time fighting element. They could probably make a pretty badass one if the MotionPlus is as accurate as they claim.
My brother and a few others seriously enjoy golf games on the wii. But the slight twitchy actions of the wiimote can ruin an otherwise perfect swing etc. though no fault of the user. Its his and pretty much everyone else's biggest complaint.
If this truly cures that, it will make for a great gameplay experience. And as noted by mustwarnothers should translate well into other aspects. The most enjoyable sword action type game so far on the wii for me was soul calibur legends. It could have been better and longer but it was still a good time.
Check out this video from E3. http/www.gametrailers.com/player/36398.html
Shows some sword action from the wii sports resort game that is also coming with a motion plus add-on. Looks like it will increase the control you have big time. I also hear that the PDGA (pro disc golf ass.) is making a disc golf game based on this. Should be sweet!!!