Hi Mr. Venkat, First let me send to a hearty thanks for your amazing book "Practices Of An Agile Developer". Which other scripting language that it could contend (or it is already contending) with Groovy over 'Preferred Scripting Language For JVM' crown? While Groovy has a smooth learning curve for Java developers, aren't other languages like JRuby and Jython are much more robust? Thanks.
A number of languages are currently being developed. Certainly you want to think about stability, features, and robustness, in addition to other factors, when selecting a language. Groovy has come a long way since its 1.0 days. The features and robustness of Groovy 1.5 is far better than 1.0 itself. Also, there is very strong community and active development behind Groovy.
Since stability and robustness is not a major concern (as it is stable and robust IMO), I suggest looking at other facts. If you are interested in a Java like syntax, preserving Java semantics, working closely with Java API, ... and want to take advantage of a dynamic language, Groovy is a better choice. If you are from other language background or already familiar with Ruby, your project really has nothing to do with Java, but you want to take advantage of the deployment advantage of the JVM, then I don't see a compelling reason to look at Groovy. Other languages (like JRuby, ...) may be more interesting in this case.