One of the new features of the 3.0 firmware is numerical battery. This feature, which has been available for jailbroken iPhones for a long time, lets you see the percentage of the battery left. It’s a really neat feature as I think it’s more accurate that the little battery logo to figure out how much battery you have left.
It took me a while to find out how to activate the battery percentage as this feature is kinda burried in the settings.
To turn numerical battery on, simply go to Settings > General > Usage.
Feel free to contact me should you have tips & tricks about the new iPhone 3.0 firmware.