There is an updated version of this article: jQuery HTML Templates: 3 Solutions to get you started
When you have a lot of AJAX calls on your website, especially ones that return a list of data, it can be quite expensive processing time on the server to retrieve the results, format them with HTML, and return them to the browser to display – not only that, your bandwidth costs can be quite high as well. With jQuery templates, you can alter your AJAX calls to return JSON leveraging Javascript event handlers, and then populate the content client-side providing faster response times and less server processing as well from an external file or JSON object.