iWebKit is a web toolkit designed to create iPhone and iPod touch compatible websites and webapps. It is very easy to use, extremely fast, compatible and extensible. iWebkit is available under GNU license and can be downloaded from http://iwebkit.net.
iWebkit theme for drupal is to make your drupal websites iPhone/iPod compatible.
An important part of building mobile websites is automatic detection of the user-agent (mobile device) so you can switch to an appropriate theme, or re-configure the layout for your mobile browsing. Once you've detected the device, you can present the website in a theme tailored to it.
Few modules to detect user-agent(browser) and switch drupal theme to appropriate mobile device compatible theme are:
* Mobile Tools http://drupal.org/project/mobile_tools is a very advanced module targeted both towards making a mobile version of your existing Drupal site, and detecting user agents for switching theme to mobile theme. A good tutorial how to use this module is available here.
* WURLF http://drupal.org/project/wurfl is module provides an API for to detect which device is accessing the site and also determine the device's capabilities (e.g. screen size, support for ajax, which device, touch_screen, etc ...). WURLF is available for download from SourceForge (it's an opensource project).