We played around with Greg Borenstein's $.srender (based on John Resig's JS templates) and Rizqi Ahmad's chain.js (http://wiki.github.com/raid-ox/chain.js/demos). We liked chain.js's syntax but wanted $.srender's speed. In addition to which we were looking for something that would be valid XML / XHMTL so that the page could be previewed before actually running the template itself. So Jeff came up with YATE (http://labs.mudynamics.com/2010/03/19/yate-javascript-templating-engine-for-agile-ui-development/), Yet Another Templating Engine.
Would appreciate your feedback.