The consumer JRE was announced at the JavaONE conference - it improves the cold startup as well as minimizes the initial footprint. Consumer JRE makes Java SE interesting as the RIA-platform for rich, but still maintainable applications. Especially interesting is the combination with the OpenSource (openJDK) strategy together with consumer JRE. It makes JDK (with consumer JRE) a candidate for bundling with some browsers like mozilla or safari. Having e.g. JRE be installed on every mozilla browser out-of-the-box and be easily installable on IE or Safari makes applets and WebStart applications a great alternative to AJAX.
Then it could be possible to build/debug/profile the full stack in one language and one IDE. The availability of Java FX Script could even improve the situation providing support for 2D vector grahics and so nice looking frontend. There is still lack of great designer tools - but there are already some impressive samples available.
I'm already looking forward for JDK 1.6 u4 to try it out :-).
NEW: Online Workhop Effective WebApps without Frameworks is also coming to: MUC Airport.