jQuery mobile has now been released. This version supports all target platforms including blackberry 5+, Windows 7, Android 2.1+ and iOS 3.2+ which should just about cover nearly all current smartphones. It supports graceful degredation of older devices too.

Accessibility is also built in, and in theory if you wanted to make a desktop version of a website specifically for visually or physically impaired people, then using jQuery mobile could be an option - the text size can be made quite large and html buttons are converted into quite big and chunky buttons on a desktop browser. This is perfect if you find it difficult to read text on a web page, or if you have unsteady hands and require large buttons. The code would also be good for people using screen readers.