A number of us at work have personal iPhones. All different generations. We love it. We all get emails. The subtle yet unmistakeable, natively uncustomizable, and only available sound effect that ALL iPhones make when we receive an email make each of us jump and/or reach for our iPhones. As a previous BlackBerry owner that have felt "phantom" vibrations, I've also learned not to trust my sense of touch as much as I would my sense of hearing. So, it's no consequence that I must rant and say that after four generations of OS, I think it's high time we get a customizable email sound effect without having to resort to jailbreaking (considering that the iPhone 4 is not yet even jailbreakable).