Este framework, nunca mejor ganada la denominación, está entre los mas completos y ricos que he visto para desarrollar aplicaciones web "ricas", me atrevería a decir que le saca bastante ventaja a todos los demás ya que cubre un espectro muy amplio de las necesidades de de las aplicaciones web. Verdaderamente vale la pena verlo y tenerlo en cuenta.
Reactive-web is a new framework for writing highly interactive and dynamic web applications. It's written in Scala , sits on top of Lift, and uses the Functional Reactive Programming library reactive-core (it's in the same repository).
As in GWT, you can code the user interface in the same language as the rest of your application (except in Scala instead of Java), rather than writing JavaScript. Unlike GWT, however, you don't need an extra build step to convert your code to JavaScript. You can easily combine code that runs on the browser with code that runs on the server. And, you can declare dynamic relationships between components, like binding in Flex/JavaFX/etc. (only much more powerful).