Scripting technologies enable developers to develop applications in new ways. The traditional development cycle biased towards the server is quite slow, and it may be even impossible if the developer has no access to the server.
Inside Romulus there has been research about how to speed up development and enable new alternatives to create applications from the client side. One of such options is Application Script Builder, developed as a portlet. Portlets fit this approach in a quite straightforward manner, as there is a support for a configuration mode (where the application is created using scripting technologies) and a view mode (the result of the execution of the script). A more detailed description can be found in chapter 5 (section 5.8) of Report on Emerging Portal Technologies.
There is also a Roma based prototype available here.