Recently, the Zepto.js library added a Deferred module.
This is wonderful, because the absence of a Deferred module was what was keeping Rdbhost from using Zepto.
<script src="http://www.rdbhost.com/vendor/rdbhost/1.1/jquery.rdbhost.js"> </script>
The principal benefit to using Zepto in lieu of jQuery is reduced page weight. The zepto.js, callback.js and deferred.js files weigh in at a combined 63K. jQuery.js is 263K. These are unminified sizes.
The complete test suite passes with Zepto, in Chrome and Firefox.