I came into this projet to help another UI developer with the design and build of the Yell.com mobile view. This was a great project to be involved in! Lots of modern HTML5 and CSS3 work, with no limits of Internet Explorer and other desktop restraints. The project was built on the Freemarker template engine , and we used zepto.js JS library as its lighter than jQuery for faster downloads on a mobile network.
We made this for iPhone, then made slight changes for Android and Blackberry. Take a look on your mobile: yell.com.