This is a lovely feature but one I tend to forget about because old habits die hard. In iOS7 the faster way of getting to you inbox or screen of active messages is to just swipe across the screen, like you are moving the chat or email to the right. I've tried this multiple times and just be aware that you have to pull from the very edge of the screen otherwise it won't work. And if you swipe of the other side of the screen (from right to left) it gives you the time stamps for each message sent in the conversation. But if you forget this little trick the icon in the top left corner hasn't changed.
Full article here.