This is designed to be a “living” post of available materials which will hopefully be updated frequently.
Right now there’s not much, just some links, but I hope to keep adding materials, so check back!
jQuery Mobile - a separate mobile UI which has jQuery as a dependency
iAd - an update to Apple’s PastryKit, but probably intended only for ads
Jo HTML5 Mobile App Framework
YUI3 - the desktop library has taken its first steps in supporting mobile (there’s no separate version just for mobile)
Spring Mobile: an extension to Spring MVC.
MooTouch - acquired and integrated into Sencha
UiUIKit (Universal iPhone UI Kit)
CiUI - CNET iPhone UI
iUI (on Google Code) - the first library for the iPhone as far as I know.
PastryKit - Apple’s proprietary framework, peeked into just for curiousity (not recommended for use)
More from the Mobile Web series:
Part 1: The viewport metatag
Part 2: The mobile developer’s toolkit
Part 3: Designing buttons that don’t suck
Part 4: On designing a mobile webpage
Part 6: Dealing with device orientation