Check out this new iPhone JavaScript library, iUI, by Joe Hewitt. The team at Digg has already put this into practice, releasing a beta of an iPhone-optimized version of digg.com. You can view this at digg.com/iphone. If you don’t have an iPhone but want to get a virtual iPhone browsing experience, download iPhoney (mac only).

iUI is about more than just visuals, it aims to make web apps as usable as Apple’s own. One usability problem I kept witnessing in early iPhone web apps was a lack of support for the back button. While using these apps I often found myself hitting back and being sent two or three “pages” backwards. The reason is that most apps are using single-page navigation, which skirts the browser’s own history. The single-page model is the right way to go, but it is imperative that the back button still works, because if I’m going to wait 3 minutes to load a page over EDGE and then have to load it again because the back button accidentally sent me away from your site, I’m not going to be happy.

That’s why I think the best feature of iUI is that it makes single-page navigation usable. It keeps the back and forward buttons working and optionally inserts a captioned back button into your app’s toolbar. It slides smoothly between pages (at least as smoothly as Safari can go, which is about 1/10th as smooth as native apps) instead of the unpleasant flicker and jumpiness that accompanies a fresh page load.