First title to do support it so far
People may remember me posting news about a game called "Rage of the Gladiator" a few months back. The game was pretty much a fantasy/gladiator arena style version of Punch-Out but with weapons & finishing moves.
There was some bitching that it was going to be played WITHOUT motion controls. Well Ghostfire Games have listened to gamers complaints and as well as adding standard motion controls, they have added Motion Plus too making it the first WiiWare title to support the add on.
Motion+ Trailer:
Like most WiiWare titles there is no release date but Ghostfire expect the game to appear on the service sometime this year.