another groovy on grails fan here... I wish more people would give it a try.. its surprisingly expressive like ruby or python , scales with the JVM, backing of all currently java libs, and great web framework like rails.
This is a serious question: several people I respect (who are smarter than me and thus well capable of learning new languages) are using Groovy for their projects and I am wondering why?
Also, Groovy's syntax is very Java like. In fact, Groovy is pretty close to a superset of Java, so you can often - if not always - rename a .java file to .groovy, and compile it with groovyc and run it. This makes it easy to leverage your existing knowledge of Java, while slowly working in the idiomatic Groovy.
All of that said, I personally plan to learn both Scala and Clojure as well; and will probably take my Scala book to the Triangle JVM Hack Night meeting tomorrow night and spend a couple of hours poking at Scala.