I did a study of the bigger templating systems available on Java earlier this year and the landscape wasn't that great: JSP, Freemarker, Velocity and a number of smaller projects. We decided that it was worth some time developing a system inspired by Django's lightweight syntax. If you send me a note (matthew@mastracci.com), I can let you know when we get our project up on github. It's rendering every page on gri.pe right now and has been stable for a few months now.