In case people haven't heard, the jQuery Mobile team have just released 1.0 Final. I haven't looked too much into it yet but it looks nice with all that browser compatibility.
jQuery Mobile: Touch-Optimized Web Framework for Smartphones & Tablets
A unified, HTML5-based user interface system for all popular mobile device platforms, built on the rock-solid jQuery and jQuery UI foundation. Its lightweight code is built with progressive enhancement, and has a flexible, easily themeable design.