In Lion, neither the previous version of FaceTime Version 1.1 (258) from OS X 10.7.1 nor the current Version 1.1.1 (262) from OS X 10.7.2 can use external iSight's Firewire mic.
The firewire iSight camera works with Lion's FaceTime, but the iSight's Firewire mic is not available for selection in FaceTime > Video. One alternative is to use another video chat app such as iChat or Skype. Both iChat and Skype can use external iSight's mic in Lion (and earlier Mac OS versions.)
More info and workaround suggestions are available here: http://discussions.apple.com/message/16216276
BTW - You are NOT addressing Apple here: http://discussions.apple.com/static/apple/tutorial/tou.html
We are just users like you trying to help others. You can send feedback directly to Apple via http://www.apple.com/feedback/macosx.html
You will not get a response, but you can be certain that the responsible Apple people will see your input for consideration in FaceTime product development.
Message was edited by: EZ Jim