Nintendo just announced their new motion-sensing peripheral, the Wii
MotionPlus, as an addition to the Wiimote. As far as we can tell, the
Wii MotionPlus is a small, white plastic box that snaps on to the
bottom of the Wiimote where you would plug in the Nunchuck. Supposedly,
the Wii MotionPlus will more accuratly reflection movements in a 3-D
space, giving players a true 1:1 response between their Wiimote and the
action on screen. Not much more information is available, but as soon
as we get the details as to what makes this magic white plastic box so
special, we'll let you know.
Source-
http://e3.g4tv.com/e32008/blog/post/687003/Nintendo_Announces_Wii_MotionPlus.html