PhoneGap is a popular framework for creating cross-platform applications. The main advantage is the possibility of using the same code on various platforms. But that's not fully correct, because PhoneGap is a native WebView component, which has an HTML5/JavaScript application; and which is able to access the native functions of a mobile device (accelerometer, compass, contacts etc.).
Choosing platforms for a PhoneGap application
Currently PhoneGap supports...