Originally Posted by
rknowlt Put your finger on the silent switch and give your phone another shake. I remember the first time I heard my 3G rattle and was concerned, but I realized after a few minutes of investigation that it was just the silent switch moving slightly. If it is just the switch then no worries, if its something else then its off to the apple store.
Yeah, it's the ringer switch. That's good to know. I still hate hearing things rattle

Oh well, at least it's nothing that'll damage performance.