Starting in PhoneGap 0.9.5 there’s an undocumented iOS only feature that allows you to handle whether the device should rotate to a particular orientation. It exposes the iOS Objective-C method shouldAutorotateToInterfaceOrientation with a JavaScript function shouldRotateToOrientation.

function shouldRotateToOrientation (rotation) {
    switch (rotation) {
        //Portrait or PortraitUpsideDown
        case 0:
        case 180:
            return true;
        //LandscapeRight or LandscapeLeft
        case 90:
        case -90:
             return false;
    }
}

This needs to be in the global scope of your JavaScript and will get called before any rotations occur, so keep it lean to avoid locking up the UI. Returning true allows the device to rotate, returning false prevents it.

Works great in your HTML5 iOS, iPhone and iPad apps, sadly currently there’s no Android or other platform integration. Hopefully we’ll see a cross-platform method soon!