Enable Wi-Fi While In Airplane Mode
One of the lesser-known goodies included in iPhone 2.0 is the ability to use Wi-Fi while in Airplane Mode. To do this, simply enable Airplane Mode and then switch on Wi-Fi. The orange airplane icon will stay in the status bar and Wi-Fi will be enabled.
Apple says that the feature is good for those on Wi-Fi enabled planes, but it may come in handy if you’re in an area with no cell reception (such as basement or college building).