The Spring framework supports the use of scripting languages (specifically JRuby, Groovy and BeanShell) whereby a script in any of these can call Java code and vice versa.
I have read that a possible use of this feature is when some modules require frequent changes and it would allow to modify your application without having to redeploy it. I have been trying to visualize a possible usage but this sounds too vague to me. I tend to associate things that can change with configuration, data or rolling a new feature in an application, but not with an existing module whose behavior can change frequently.
In summary: when did you benefit from using Spring scripting or at least what would be a realistic, concrete example?