Wicket, I suggest.
With proper mark-up/logic separation, a POJO data model, and a refreshing lack of XML, Wicket makes developing web-apps in Java simple and enjoyable again. Swap the boilerplate, complex debugging and brittle code for powerful, reusable components written with plain Java and HTML.
It's V1.3.0 coming.
I started looking at feasibility of using Grails to provide required functionality.
Benefits of Grails:
- Groovy is a natural choice for scripting, but complied language, that can produce scalable applications.
- Can provide compiled execution
- Can execute user created script in controlled security context
- Draw on richness of Java
- Good XML, RSS, SOAP, REST support
- Grails provides all tools required for implementing framework fast
- URL mapping and manipulation tools enable user-friendly URLs
- Template and layout functionality can easily enable skins and personalised layouts
- Hibernate and Spring provide good base for applications
Risks and cons:
- Grails is young
- Use of Spring Web dictates how it interacts with Servlet container
JRuby + Rails
The team at Sun have done some great work on JRuby.
I know that Alfresco is Java and Groovy + Grails has a Java heritage, but reading through the WSF wiki goals I think JRuby better meets your needs.