I really want to try that, especially since they also support Groovy, if I remember correctly.

On the other hand, what puts me off is that it seems to require an application container. I wonder if that would have been the case if it had not been developed by employees of JBoss... So far I was very happy with Tomcat, and I am reluctant to move to a full-fledged application server.

It works in tomcat just fine (I hear). Apparently they have examples that show it deploying to it. And other ones as well. Yeah I heart the groovy thing as well. Ruby maybe forthcoming, problem is ruby doesn't have the same sort of java like annotations that groovy has (and seam expects).