Imagine your sister is away at school and can¡¯t make it to your son¡¯s birthday. So you¡¯re cheering her up with a FaceTime call. As the cupcakes come out, your son¡¯s eyes light up, and you just have to share it. Tap a button, and before you can say, ¡°Make a wish,¡± iPhone 4 switches to the back camera, and to the birthday boy's big moment. Another tap switches back to the front camera and to you. Simple, fast, and fun.