Although the small lightning logo appears next to the battery icon when charging the iPhone, I still find it difficult to quickly discern whether or not my device is charging. For whatever reason, it always takes me a second or two to realize that the lightning icon is there, indicating a charge.
With a tweak like ChargePulse, you can easily spot when your iPhone is charging, even when it's two to three feet away. ChargePulse makes it readily apparent that your battery is charging by adding a subtle pulse to the battery icon in the status bar.