I’m not an advocate of building iPhone web apps because no matter how hard you try, your iPhone web app won’t be as smooth, responsive, and polished as a native app.
But if you really want to try to build an iPhone web app with a native feel, take a look at this article for some good advice:
http://cheeaun.com/blog/2012/03/how-i-built-hacker-news-mobile-web-app