How to create Android Back Button handler:

phonegap 0.9.5 and later:

// This is your app's init method. Here's an example of how to use it
function init() {

    document.addEventListener("deviceready", onDR, false);

} 

function onDR(){
    document.addEventListener("backbutton", backKeyDown, true);

    //boot your app...

}

function backKeyDown() { 

    // do something here if you wish

    // alert('go back!');

}

phonegap 0.9.4 and earlier:

// This is your app's init method. Here's an example of how to use it
function init() {

    document.addEventListener("deviceready", onDR, false);

}

function onDR(){
    BackButton.override(); 
    document.addEventListener("backKeyDown", backKeyDown, true);

    //boot your app...

}

function backKeyDown() { 

    // do something here if you wish

    // alert('go back!');

}