Gmail on the iPad and iPhone are two of the best mobile interfaces I have used. They are snappy, they allow me to do many things, and they look really good doing. These 2 older articles describe some of the innovations used in the iPad an iPhone/android user interfaces. For example they use the canvas tag to create the loading icon instead of downloading images. They also make extensive use of offline downloading. They also describe using CSS3 transforms to keep the floaty bar in place. These features not only look cool, but are used to speed everything up and make it more accessible offline. I'm really want to start playing with HTML5 Manifest (offline mode). Check out the two blog posts.