With iOS 7.1 beta 2 Apple added a new viewport meta tag that allows us to minimize the top and bottom bars in Safari on the iPhone. It'll be basically the same behaviour as if the user starts to scroll. In the past we had to do this with a little trick and trigger the behaviour with a 1px scroll when the page was loaded.
I think even though it adds annoooother option to the viewport meta tag which can get a little cluttered, it's a good addition:
<meta name="viewport" content="minimal-ui">