Since everyone is talking about developing for mobile these days and how it became a must, jQuery released the "jQuery Mobile" framework that is:

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.

My only(and huge) problem with it is that it lacks any RTL support. Luckily, Moutaz Shams decided to do something about it and RTLed the framework. Now how cool is that? =)

You can try and download this unofficial release at http://www.intlaqa.com/jquery-mobile-rtl/

Hoping jQuery will consider RTL support in an official release in the near future. Maybe they'll consider the jQuery UI widgets too