I have been using GWT with App Engine for a while now. Recently there was an announcement that GWT will support Spring Roo and SpringSource Tool Suite (http://googlewebtoolkit.blogspot.com/2010/05/gwt-21-milestone-1-is-now-available.html). I am having trouble seeing the big picture from the Google announcement page. For those without much knowledge of Spring what does this mean for GWT developers used to building swing-like gui's?
My understanding is that Spring-Roo simplifies creating the server side component as well as making a rudimentary GWT front end for you. Then as a GWT developer, you can take the generated GWT front end and further embellish it. So, if is as good as they say it is, it makes your life as a GWT developer much easier and makes you more productive.
I think that this alliance enables developers to design complex and high performing applications even more easier. Concering GWT applications Spring would offer the server-side part with the many aspects provided by the framework (e.g. dependency injection, architecture, securits, data access ...) you might need in an enterprise application. As far as I understand Spring Roo is a framework for rapid developement. Using GWT in combination with this, GAE and other mentioned spring technologies you'll be able to quickly start developing app engine applications (for example).