Although there hasn't been an official announcement yet, we expect to see the Wii-mic by Q3. Rumors have surfaced and GoNintendo confirmed that NDA was broken -- so, yeah, about that Wii-mic. The writing was on the wall earlier this week when High School Musical was announced for the Wii. The Karaoke Revolution-esque game by Disney Interactive will use a microphone. Unless the game is using the Gamecube's mic to be stuck in on top of the Wii, that means a microphone attachment will soon be officially announced by Nintendo.
The real NDA breaking rumor has EA working on a Harry Potter game using the mic in conjunction with gestures to cast spells. Now that's the type of Wii title we're talking about! "Wingardium Leviosah" FTW! Sadly, those who attended the EA Wii event on Wednesday signed NDAs -- so there's a lot of people out there sitting on information they can't confirm, deny or share with their readers.
Update: Statement from GoNintendo, "The NDA I am talking about has nothing to do with the mic for the Wii. I was just mentioning the mic part because we already knew it was coming according to High School Musical info. The NDA deals with something else completely. If EA talked about a mic at their party, I didn't hear anything about it. "