I just got back from EB with my two WaveBirds. So does the WaveBird receiver get in the way of the drive door? The world wants to know....
The WaveBird receiver does NOT interfere with the Q's drive bay. If you have a Q, the WaveBirds fit just like they would with a regular GameCube, except the receiver juts out a little bit more due to the contoured design of the wireless receiver's backside.

The WaveBird works just fine with the Q. Thank you Nintendo!