MUIkit is a HTML, CSS and jQuery framework. You can use this framework to create mobile friendly Web Sites/Web Apps. This project is inspired by various UI elements found on todays mobile devices, which include iPhone and Android.
Google, Yahoo and other companies have their own mobile frameworks/libraries (Google News for example). This framework can be used to build such browser based apps with ease.
There are some projects on the internet, which imitate iPhone interface pretty well. This is not only inspired by the iPhone UI, it also takes the best UI elements from other platforms too. And the other thing worth mentioning is, it aims to be cross browser.
Developmental Preview : http://mohansandesh.com/MuiKit/index.html (Best viewed on a mobile device)
These details are provided for information only. No information here is legal advice and should not be used as such.