The Sencha Touch API is pretty amazing and is awesome. As far as I have seen it helps you with application developement for mobile/IPad and works well in Safari and webkit. Google Chrome too...:)
But it did not work with IE/Firefox....
Go through the video and I am sure you will thirst for more....
Sencha Touch - Intro to Layouts from Sencha on Vimeo.
The following site contains more such videos and they are all awe some
hope this helps :)