Old trick with window.scrollTo(0,1); doesn\'t work. And even worse, the address bar moves only a bit and gets stuck halfway out sometimes.
It is a combination of many things as I have found when researching this issue for myself. Here's the code that properly works on iOS5: (I know I'm a little late, but an answer is an answer, hopefully it can help people in the future)
Hide Address Bar
Content
Source: http://24ways.org/2011/raising-the-bar-on-mobile
Example: http://jsbin.com/isenax/