Since the announcement of Wii motion plus at E3 2008, it was slated to pack in with the eagerly awaited WiiSports Resort. That was supposed to be this spring, and wait... it's spring right now.
One delay after another has left us all wondering, but it seems it's not the add-on that's holding things up because now it's slated for release July 2nd with EA's Grand Slam Tennis for €59.99 or €49.99 without the accessory. Other games expected to utilize Motion Plus soon include Red Steel 2, Tiger Woods 2010 and Virtua Tennis.
The add-on connects to the base of the Wii Remote and offers 1:1 motion tracking for increased sensitivity and accuracy with motion based games. This could also mean Wii Sports Resort may not be far behind. Keep hope alive.