we are in the planning stage of migrating a large website which is built on a custom developed mvc framework to a java based web framework which provides built-in support for ajax, rich media content, mashup, templates based layout, validation, maximum html/java code separation. Grails looked like a good choice, however, we do not want to use a scripting language. We want to continue using java. Template based layout is a primary concern as we intend to use this web application with multiple web sites with similar functionality but radically different look and feel.

Is portal based solution a good fit to this problem?

Any insights on using "Spring Roo" or "Play" will be very helpful.

I did find similar posts like this, but it is more than a year old. Things have surely changed in the mean time!

EDIT 1: Thanks for the great answers! This site is turning to be the best single source for in-the-trenches programmer info. However, I was expecting more info on using a portal-cms duo. Jahia looks goods. Anything similar?