iPhone dropped from the top on my Desktop
The inside of an iPhone is all solid state and can tolerate being dropped. That said, you should thoroughly test the hardware on your phone to see if anything broke. This includes the screen, case, the touchscreen (make sure that touch and multitouch still works everywhere), the headphone jack, all the buttons, the camera and flash, and the dock connector. A bump could have misaligned or disconnected any of the above hardware.