I've got a bit an intermittent problem with my Apple in-ear headphones and voice control on my new 3GS. I click and hold the in-line button and the voice control tone sounds. I make a command and it works. Then moments later, when I try again, it won't work. I get the tone, but the lines on the screen don't oscillate when I speak, suggesting there's no audio being received by the microphone. Then a few moments later, it will work again. I'm certain it's the headphones as I have a B&O earset 3 and it seems fine with those. Have I just got a poor pair of Apple in-ears?