I'm on the fence. I answer my cell phone and hold brief conversations, on bike or car (though I'm not in car much these days). I don't like drivers who are talking on the phone in city traffic, and although I haven't seen cyclists do it I probably wouldn't like it either. The difference is--they aren't holding brief conversations.

I have mastered the art of extracting my phone from the seat pack, and I just learned riding with no hands. I absolutely love it. I do the "Titanic". (You know, where she is standing on the rail of the ship with her arms straight out. I stand on my pedals and hold my arms out.)