In ioS 6 and earlier, double clicking the Home button opens the app switcher. This has not changed with the release of iOS 7, but the format of the app switcher has.
<p>The app switcher experience in iOS 7 remains relatively unchanged in iOS 7. Flick left or right to move between the apps on your device. VoiceOver will now announce the status of that app. For example, VoiceOver will announce, "running" when an app has active background services VoiceOver will announce the home screen option when you flick left to the first option in the list of the open app list. Double/split tapping this option will bring you to the last visited page of the home screen. <h2>Closing Apps</h2> While in the app switcher flick left or right to find the app you would like to close and swipe up with three fingers to close it.