Then there's TrimPath, which looks like what Steve is trying to do, with Google Gears integration, alleged Ruby on Rails-like MVC and a lot of other good stuff to boot. Another feature of TrimPath is that is can execute on either the server or the browser, just like Jaxer.
This brings us quickly to another class of SSJS, namely the Mozilla Rhino integrated Java-based frameworks, like Apache Sling, for instance. Sling _is_ an über-JCR implementation which uses REST for object management, can be a webDAV server and is violently OSGi compliant :) But for the purpose of this discussion - it most importantly has a generic Scripting support, letting you script resource behavior in JSP, JRuby and, yes, SSJS.
Sling is probably not the last framework to enable productivity by simplifying development by allowing server-side scripting inside a 'classical' framework - Sling being anything but, but you understand what I mean.
But back to Jaxer. Is jaxer really an also-ran even before it came out. Does it have anything to contend with beside these other frameworks?
Well, yes, actually it has. Jaxer has (not yet) integrated support for any Java class in classpath - which should be in their number five priority list), but it has server-side DOM rendering.
Huh? But the DOM is on the client..
Not any more baby, check out these pix and see what I mean. Jaxer can take any HTML/js/css combo, and if you want execute the (standard) jQuery calls to set up the markup the way you want, and then sent the finished, static page to the client.
It could, for instance, detect if your poor user was forced to use a version of Internet Explorer, and then use the Mozilla engine included in Jaxer to render the page on the serve, and give them the right page looks anyway. How's that for flexibility.
Also, Aptana has financing, has released Jaxer under GPL, and has integrated Jaxer (which can be standalone as well, as an Apache mod) into their Eclipse-based IDE, Aptana Studio.
Yes, I like Jaxer, and I like the Studio as well, in case you didn't notice :) But what Aptana really need to do is to check out their SSJS competition and offer framework services, Java, and possibly PHP integration and more out-of-the-box programmableweb.com services. And more Dojo. Lots of Dojo.
Actually, the SSJS (non-web) framework issue was on the top of my mind when I started writing this, but I'll have to get back to it later, due to bed-putting constraints .