HTML::Template is a popular and well-designed HTML template system for Perl.
As an alternative to Jemplate, there’s now HTMLTemplateJS, a Javascript implementation of HTML::Template.
Of course, just like Jemplate, templates are precompiled into Javascript functions and it also supports caching.
And although it wisely use the Prototype framework, the HTMLTemplateJS system is only 3.5 Ko large (minified+gzipped).
Thanks to Mixi’s engineers for the discovery.