On the Zend Developer Zone today there's a new tutorial from Vikram Vaswani about using the Spidermonkey Javascript engine together with the PECL extension for it to create a few simple examples.

Not too long ago, it seemed like there was a pretty clear distinction between client-side technologies and server-side technologies. [...] Things aren't that clear any longer. [...] And in this article, I'm going to show you how to add a JavaScript engine to your PHP build, with a little help from PECL's SpiderMonkey extension.

The PHP extension lets you use the libraries (with your PHP 5.3+ installation) to directly create new objects and work with the Javascript like it was PHP. The end result is then passed out to the browser via a "evaluateScript" call. He illustrates how you can use objects and generate XML quickly and easily.