I discovered this yesterday, as just wondered if it was apparant in all iPhone 3Gs. If it's real quiet (at night, for example), if I plug my earphones in, and do something such as load an app, swipe between home screens, scroll, or anything like that, I can hear what sounds like a hard drive spinning. It stops when I stop scrolling, or the app has loaded or whatever. It's real quiet, and can only be heard through the earphones which is weird as I'm guessing a hard drive spinning wouldn't be a digital noise... Anyone else noticed this?