“Zepto.js is a minimalist inlinable framework for mobile WebKit browsers, with a jQuery-like chaining syntax.” — I like the bigger picture behind this: don’t include a full jQuery on a mobile site but go back to basics and serve visitors a tiny javascript file which handles most of the stuff.
Somewhat (in an idea-wise manner) related is The Facebook Frontend Tech Talk where they explain how they’ve written a tiny piece of code that handles about 80% of all interactions and which doesn’t block the UI Thread.