WiimotionPlus is an add-on for the Nintendo Wii Wiimote (it plugs in at the bottom) which provides you with greater motion-sensing capabilities while playing. It only applies to a few new titles right now including EA Sports Grand Slam Tennis, Tiger Woods PGA Tour 10, and Virtual Tennis 2009.
According to the official Nintendo website "Wii MotionPlus brings every twist of the wrist or turn of the body to life, faithfully replicated on the TV screen. See the swing of a golf club or the slash of a sword revealed in vivid 1:1 movement - Wii MotionPlus elevates Wii gameplay to a level of realism that you never thought imaginable."
I bought it in a bundle at GameStop withTiger Woods and I was amazed. Nintendo is introducing to us a new world of gaming and this is just the beginning.
Before the Wii controls were relatively basic but Wii Motion Plus is giving you more precision and accuracy. It has better response so you're no longer just playing a simulation of a game that's been simplified, you're actually putting real skill and getting more physically involved!
The downside is that it costs $24.99. Come on Nintendo, these are tough times. Sure this is a cool add-on but come on.. 25 bucks?!