Sad to say but it doesn't add much value and it makes certain tasks harder even. For instance it makes it very hard (or almost impossible) to use that same html templates on the backend and on the frontend side of things.
pajama.js (pjs) is a serverside and clientside templating engine...
GitHub only has the first commit so I don't think it is production ready but I find the idea to be novel and interesting.P.S. The <title> on http://www.pajamajs.com/ is not set yet.